Code
P1480
BUICK
P — Powertrain
Cooling Fan 1 Control Circuit High
Views:
UK: 27
EN: 53
RU: 24
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
CADILLAC
P — Powertrain
Cooling Fan 1 Control Circuit High
Views:
UK: 28
EN: 43
RU: 21
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
CHEVROLET
P — Powertrain
Cooling Fan 1 Control Circuit High
Views:
UK: 23
EN: 42
RU: 21
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
CHRYSLER
P — Powertrain
Cooling Fan 1 Control Circuit High
Views:
UK: 25
EN: 43
RU: 20
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
DODGE
P — Powertrain
PCV Solenoid Valve Open Or Shorted
Views:
UK: 26
EN: 49
RU: 26
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
FORD
P — Powertrain
Fan Secondary Low with Low Fans On
Views:
UK: 28
EN: 46
RU: 24
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Your experience will help others
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Send to email
Code
P1480
GM
P — Powertrain
Cooling Fan 1 Control Circuit High
Views:
UK: 24
EN: 41
RU: 18
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Your experience will help others
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Was this AI description helpful?
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Send to email
Code
P1480
GMC
P — Powertrain
Cooling Fan 1 Control Circuit High
Views:
UK: 29
EN: 43
RU: 21
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
HUMMER
P — Powertrain
Cooling Fan 1 Control Circuit High
Views:
UK: 15
EN: 31
RU: 15
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
JEEP
P — Powertrain
PCV Solenoid Valve Open Or Shorted
Views:
UK: 29
EN: 45
RU: 25
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
LINCOLN
P — Powertrain
Fan Secondary Low with Low Fans On
Views:
UK: 26
EN: 43
RU: 20
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
MERCEDES-BENZ
P — Powertrain
Preglow Control
Views:
UK: 15
EN: 30
RU: 14
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
MERCURY
P — Powertrain
Fan Secondary Low with Low Fans On
Views:
UK: 29
EN: 45
RU: 24
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
OLDSMOBILE
P — Powertrain
Cooling Fan 1 Control Circuit High
Views:
UK: 26
EN: 46
RU: 19
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Your experience will help others
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0
Send to email
Code
P1480
Other
P — Powertrain
Fan Secondary Low with Low Fan On
Views:
UK: 33
EN: 49
RU: 23
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Workshop Manuals
Available brands with manuals
2
AUDI 11
6-speed manual gearbox 0B1, front-wheel drive — Workshop Manual (Edition 05.2014)
Workshop ManualAudi A3 (1997) – 1.6L 4-cylinder (2‑valve) Engine Mechanical Components Service Manual (AEH, AKL, APF) – Edition 07.2002
Workshop ManualAUDI A3 (2004) Workshop Manual — 2.0L FSI Turbo (4‑cyl, 4‑valve) Engine, Mechanics — Edition 03.2017
Workshop ManualAudi A3 2004 — Electrical System (Workshop Manual, Edition 02.2018)
Workshop ManualAudi A4 / A4 Cabriolet – 4.2 l V8 (5‑valve, timing chains) – Workshop Manual (Mechanics) – Edition 04.2007
Workshop ManualAudi A4 / A4 Cabriolet — Auxiliary Heater Workshop Manual (Edition 08.2004)
Workshop ManualAudi A4 / A4 Cabriolet (1.8T 4‑cyl turbo) — Motronic Injection & Ignition System Service Manual (Edition 01.2015)
Workshop ManualAudi A8 (2003) — Electrical System Workshop Manual (Edition 08.2014)
Workshop ManualAudi Q4 e-tron (Type F4) - Self-study Programme SSP 685
Workshop ManualAudi Q8 (2018) — Electrical System Workshop Manual (Edition 05.2019)
Workshop ManualAudi Servicing Manual — 7‑Speed Dual Clutch Transmission 0CJ / 0CL / 0CK / 0DN / 0DP / 0HL (Edition 05.2018)
Workshop ManualLAND ROVER 3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop ManualLand Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop ManualLand Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop ManualYour experience will help others
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Code
P1480
PLYMOUTH
P — Powertrain
PCV Solenoid Valve Open Or Shorted
Views:
UK: 27
EN: 53
RU: 23
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
PONTIAC
P — Powertrain
PCV Solenoid Valve Open Or Shorted
Views:
UK: 27
EN: 53
RU: 20
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
RAM
P — Powertrain
PCV Solenoid Circuit
Views:
UK: 7
EN: 11
RU: 4
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
SATURN
P — Powertrain
Cooling Fan 1 Control Circuit High
Views:
UK: 23
EN: 44
RU: 22
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
P1480
SCION
P — Powertrain
Cooling fan relay circuit malfunction
Views:
UK: 4
EN: 6
RU: 2
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Your experience will help others
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Code
P1480
SUBARU
P — Powertrain
Cooling Fan Relay 1 Circuit High Input
Views:
UK: 25
EN: 48
RU: 25
AI status
Completed
Completed
100%
Causes
- Short to battery (B+) on the Cooling Fan 1 control wire
- Failed cooling fan motor with internal short
- Stuck/failed fan relay or fused jumper stuck closed
- Corroded, damaged or loose connector or wiring causing unintended B+ feed
- PCM/ECM output driver fault
- Aftermarket wiring or incorrect repairs creating a high-voltage path
Symptoms
- Cooling fan may run continuously or not respond correctly to commands
- Engine may run cooler than expected or overcooling at idle
- Possible cooling fan noise or abnormal fan behavior
- Check Engine Light (MIL) illuminated and DTC stored
- Reduced HVAC performance at idle (if fan speed affects condenser cooling)
What to check
- Read and record freeze frame and live data with a scan tool (fan command, fan speed, coolant temp)
- Visual inspection of fan assembly, relay, fuses and wiring for damage or corrosion
- Backprobe the Cooling Fan 1 control terminal at the fan connector and at the PCM while monitoring voltage with key ON and while commanded ON/OFF
- Unplug fan connector to see if PCM sees change or if code clears (note: does not rule out PCM faults)
- Measure fan motor coil resistance and compare to specification
- Check for continuity to battery positive and to PCM ground; check for short to B+ on control circuit
Signal parameters
- Typical control topology: PCM uses low-side switching (driver to ground).
- Expected voltage when fan is commanded ON: control circuit near 0 V (low).
- Expected voltage when fan is OFF: control circuit near battery voltage (approx. 12 V) because of pull-up or internal wiring; note: measured voltages vary by design.
- If PCM uses PWM: expected PWM frequency typically in the tens to several hundred Hz (vehicle-specific).
- A 'High' fault means the control circuit voltage is higher than the PCM expects for the commanded state (often indicating a short to B+ or driver issue).
Diagnostic algorithm
- Safety: work on a cool engine, disconnect battery if performing connector repairs, and use fuses/jumpers and PPE.
- Scan tool: read and record PIDs and freeze frame, then clear codes and attempt to reproduce to confirm current condition.
- Visual: inspect fan connector, wiring harness, relay, and fuses for corrosion, melted insulation, pin damage, or aftermarket splices.
- Backprobe testing: with key ON (engine off), backprobe the fan control wire at the fan connector. Command fan ON/Off with a scan tool and observe voltage. If commanded ON and voltage remains near battery (no pull to ground), suspect short to B+ or open driver.
- Isolate load: unplug the fan connector. If the circuit voltage returns to expected values or the DTC no longer sets, the fan assembly or harness is likely at fault. If code remains with fan unplugged, suspect PCM or wiring short upstream.
- Motor and relay tests: bench-test fan motor by applying 12 V through a fused jumper to verify it runs and does not draw excessive current. Test or swap the fan relay if used in the circuit.
- Wiring checks: use an ohmmeter to check continuity between fan control terminal and PCM terminal, and check for short to battery positive (low resistance to B+ indicates short). Wiggle-test harness to reproduce intermittent faults.
- PCM check: only after verifying wiring, connectors, relay and fan assembly are good should you suspect PCM driver failure. Confirm with manufacturer diagnostic procedures before replacing PCM.
- Repair and verify: repair or replace damaged wiring, connectors, relay or fan assembly; clear codes and verify proper operation under all conditions (idle, commanded on, cooling cycles).
Likely causes
- Wiring short between fan control circuit and battery positive
- Faulty fan relay contacts welded closed or relay stuck in ON position
- Cooling fan assembly internal electrical fault
- Poor connector pin fit or corrosion at fan connector or PCM connector
- PCM output transistor failed and sourcing voltage
Fault status
Status
Cooling Fan 1 Control Circuit High — ECM detected higher-than-expected voltage on the fan 1 control circuit; possible short to battery, faulty fan/relay wiring, or PCM driver failure.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Your experience will help others
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Was this AI description helpful?
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0
Send to email