Code
B1259
ALFA ROMEO
B — Body
Solar radiation sensor open circuit
Views:
UK: 14
EN: 37
RU: 19
AI status
Completed
Completed
100%
Causes
- Open or broken wiring between sensor and control module
- Disconnected, corroded or damaged connector at the solar sensor
- Faulty solar radiation sensor (internal open)
- Blown fuse or lost power/ground to sensor circuit
- Water ingress or physical damage at sensor location
- Control module input circuit fault
Symptoms
- Automatic climate control not compensating for sunlight (cab temperature drift)
- A/C or blower runs incorrectly on AUTO mode
- Climate system displays a fault or reduced functionality
- DTC B1259 stored in HVAC/body control module
What to check
- Use a scan tool to read stored codes and freeze frame data; note ambient/solar sensor live values
- Visual inspection of sensor mounted on top of instrument panel (near windshield) for damage, debris, or water intrusion
- Inspect connector and wiring for corrosion, bent pins, looseness, or damage
- Check related fuses and accessory power/ground circuits
- Backprobe sensor connector and verify reference power, ground and signal with ignition ON
- Measure continuity between sensor signal pin and the control module pin with connector disconnected (check for open circuit)
Signal parameters
- Type: low-voltage analog signal (solar irradiance sensor)
- Typical signal range: ~0.0–5.0 V (dark to bright sunlight) — value varies by manufacturer
- Open-circuit symptom: no signal (infinite resistance) or sensor voltage stuck at 0 V
- When present, sensor changes voltage proportionally with incident sunlight
Diagnostic algorithm
- Connect a diagnostic scan tool. Confirm B1259 and note freeze frame/live data values for solar and related sensors. Clear codes and see if code returns.
- Perform a visual inspection of the solar sensor location on the dash and its connector. Look for water, debris, or physical damage.
- Check fuses and verify the sensor has proper reference power and ground with ignition ON. Repair any blown fuses or supply faults.
- Backprobe the sensor connector: measure signal voltage at the sensor with ignition ON and varying light on the sensor (shade/unshade). Expect low voltage in dark, higher in sunlight. If no voltage, proceed to step 5.
- With both ends disconnected, check continuity between the sensor signal pin and the control module signal pin. Repair any open or high-resistance wiring.
- If wiring and power/ground are good but the sensor signal does not change with light, replace the solar radiation sensor.
- After repair, clear codes and confirm proper operation with the scan tool and by exercising the climate control (verify code does not return).
- If fault remains after replacing sensor and repairing wiring, inspect the control module input and consider module diagnostics or replacement per manufacturer guidance.
Likely causes
- Broken or pinched harness under dashboard or at windshield pass-through
- Corroded/loose connector at the sensor (common on dash-mounted sensors)
- Failed solar sensor element
- Blown interior/BCM-related fuse feeding sensor
Fault status
Status
Solar radiation sensor open circuit (no signal / open wiring) stored in HVAC/Body module.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
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Code
B1259
FIAT
B — Body
Solar radiation sensor open circuit
Views:
UK: 15
EN: 32
RU: 18
AI status
Completed
Completed
100%
Causes
- Open or broken wiring between sensor and control module
- Disconnected, corroded or damaged connector at the solar sensor
- Faulty solar radiation sensor (internal open)
- Blown fuse or lost power/ground to sensor circuit
- Water ingress or physical damage at sensor location
- Control module input circuit fault
Symptoms
- Automatic climate control not compensating for sunlight (cab temperature drift)
- A/C or blower runs incorrectly on AUTO mode
- Climate system displays a fault or reduced functionality
- DTC B1259 stored in HVAC/body control module
What to check
- Use a scan tool to read stored codes and freeze frame data; note ambient/solar sensor live values
- Visual inspection of sensor mounted on top of instrument panel (near windshield) for damage, debris, or water intrusion
- Inspect connector and wiring for corrosion, bent pins, looseness, or damage
- Check related fuses and accessory power/ground circuits
- Backprobe sensor connector and verify reference power, ground and signal with ignition ON
- Measure continuity between sensor signal pin and the control module pin with connector disconnected (check for open circuit)
Signal parameters
- Type: low-voltage analog signal (solar irradiance sensor)
- Typical signal range: ~0.0–5.0 V (dark to bright sunlight) — value varies by manufacturer
- Open-circuit symptom: no signal (infinite resistance) or sensor voltage stuck at 0 V
- When present, sensor changes voltage proportionally with incident sunlight
Diagnostic algorithm
- Connect a diagnostic scan tool. Confirm B1259 and note freeze frame/live data values for solar and related sensors. Clear codes and see if code returns.
- Perform a visual inspection of the solar sensor location on the dash and its connector. Look for water, debris, or physical damage.
- Check fuses and verify the sensor has proper reference power and ground with ignition ON. Repair any blown fuses or supply faults.
- Backprobe the sensor connector: measure signal voltage at the sensor with ignition ON and varying light on the sensor (shade/unshade). Expect low voltage in dark, higher in sunlight. If no voltage, proceed to step 5.
- With both ends disconnected, check continuity between the sensor signal pin and the control module signal pin. Repair any open or high-resistance wiring.
- If wiring and power/ground are good but the sensor signal does not change with light, replace the solar radiation sensor.
- After repair, clear codes and confirm proper operation with the scan tool and by exercising the climate control (verify code does not return).
- If fault remains after replacing sensor and repairing wiring, inspect the control module input and consider module diagnostics or replacement per manufacturer guidance.
Likely causes
- Broken or pinched harness under dashboard or at windshield pass-through
- Corroded/loose connector at the sensor (common on dash-mounted sensors)
- Failed solar sensor element
- Blown interior/BCM-related fuse feeding sensor
Fault status
Status
Solar radiation sensor open circuit (no signal / open wiring) stored in HVAC/Body module.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
Similar codes
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Code
B1259
HUMMER
B — Body
The digital radio receiver detects an antenna fault
Views:
UK: 14
EN: 38
RU: 17
AI status
Completed
Completed
100%
Causes
- Open or broken wiring between sensor and control module
- Disconnected, corroded or damaged connector at the solar sensor
- Faulty solar radiation sensor (internal open)
- Blown fuse or lost power/ground to sensor circuit
- Water ingress or physical damage at sensor location
- Control module input circuit fault
Symptoms
- Automatic climate control not compensating for sunlight (cab temperature drift)
- A/C or blower runs incorrectly on AUTO mode
- Climate system displays a fault or reduced functionality
- DTC B1259 stored in HVAC/body control module
What to check
- Use a scan tool to read stored codes and freeze frame data; note ambient/solar sensor live values
- Visual inspection of sensor mounted on top of instrument panel (near windshield) for damage, debris, or water intrusion
- Inspect connector and wiring for corrosion, bent pins, looseness, or damage
- Check related fuses and accessory power/ground circuits
- Backprobe sensor connector and verify reference power, ground and signal with ignition ON
- Measure continuity between sensor signal pin and the control module pin with connector disconnected (check for open circuit)
Signal parameters
- Type: low-voltage analog signal (solar irradiance sensor)
- Typical signal range: ~0.0–5.0 V (dark to bright sunlight) — value varies by manufacturer
- Open-circuit symptom: no signal (infinite resistance) or sensor voltage stuck at 0 V
- When present, sensor changes voltage proportionally with incident sunlight
Diagnostic algorithm
- Connect a diagnostic scan tool. Confirm B1259 and note freeze frame/live data values for solar and related sensors. Clear codes and see if code returns.
- Perform a visual inspection of the solar sensor location on the dash and its connector. Look for water, debris, or physical damage.
- Check fuses and verify the sensor has proper reference power and ground with ignition ON. Repair any blown fuses or supply faults.
- Backprobe the sensor connector: measure signal voltage at the sensor with ignition ON and varying light on the sensor (shade/unshade). Expect low voltage in dark, higher in sunlight. If no voltage, proceed to step 5.
- With both ends disconnected, check continuity between the sensor signal pin and the control module signal pin. Repair any open or high-resistance wiring.
- If wiring and power/ground are good but the sensor signal does not change with light, replace the solar radiation sensor.
- After repair, clear codes and confirm proper operation with the scan tool and by exercising the climate control (verify code does not return).
- If fault remains after replacing sensor and repairing wiring, inspect the control module input and consider module diagnostics or replacement per manufacturer guidance.
Likely causes
- Broken or pinched harness under dashboard or at windshield pass-through
- Corroded/loose connector at the sensor (common on dash-mounted sensors)
- Failed solar sensor element
- Blown interior/BCM-related fuse feeding sensor
Fault status
Status
Solar radiation sensor open circuit (no signal / open wiring) stored in HVAC/Body module.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
Similar codes
Repair manuals
Manual library for HUMMER
69
Browse 69 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
HUMMER
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Code
B1259
Other
B — Body
Solar Radiation Sensor Circuit Open
Views:
UK: 19
EN: 47
RU: 32
AI status
Completed
Completed
100%
Causes
- Open or broken wiring between sensor and control module
- Disconnected, corroded or damaged connector at the solar sensor
- Faulty solar radiation sensor (internal open)
- Blown fuse or lost power/ground to sensor circuit
- Water ingress or physical damage at sensor location
- Control module input circuit fault
Symptoms
- Automatic climate control not compensating for sunlight (cab temperature drift)
- A/C or blower runs incorrectly on AUTO mode
- Climate system displays a fault or reduced functionality
- DTC B1259 stored in HVAC/body control module
What to check
- Use a scan tool to read stored codes and freeze frame data; note ambient/solar sensor live values
- Visual inspection of sensor mounted on top of instrument panel (near windshield) for damage, debris, or water intrusion
- Inspect connector and wiring for corrosion, bent pins, looseness, or damage
- Check related fuses and accessory power/ground circuits
- Backprobe sensor connector and verify reference power, ground and signal with ignition ON
- Measure continuity between sensor signal pin and the control module pin with connector disconnected (check for open circuit)
Signal parameters
- Type: low-voltage analog signal (solar irradiance sensor)
- Typical signal range: ~0.0–5.0 V (dark to bright sunlight) — value varies by manufacturer
- Open-circuit symptom: no signal (infinite resistance) or sensor voltage stuck at 0 V
- When present, sensor changes voltage proportionally with incident sunlight
Diagnostic algorithm
- Connect a diagnostic scan tool. Confirm B1259 and note freeze frame/live data values for solar and related sensors. Clear codes and see if code returns.
- Perform a visual inspection of the solar sensor location on the dash and its connector. Look for water, debris, or physical damage.
- Check fuses and verify the sensor has proper reference power and ground with ignition ON. Repair any blown fuses or supply faults.
- Backprobe the sensor connector: measure signal voltage at the sensor with ignition ON and varying light on the sensor (shade/unshade). Expect low voltage in dark, higher in sunlight. If no voltage, proceed to step 5.
- With both ends disconnected, check continuity between the sensor signal pin and the control module signal pin. Repair any open or high-resistance wiring.
- If wiring and power/ground are good but the sensor signal does not change with light, replace the solar radiation sensor.
- After repair, clear codes and confirm proper operation with the scan tool and by exercising the climate control (verify code does not return).
- If fault remains after replacing sensor and repairing wiring, inspect the control module input and consider module diagnostics or replacement per manufacturer guidance.
Likely causes
- Broken or pinched harness under dashboard or at windshield pass-through
- Corroded/loose connector at the sensor (common on dash-mounted sensors)
- Failed solar sensor element
- Blown interior/BCM-related fuse feeding sensor
Fault status
Status
Solar radiation sensor open circuit (no signal / open wiring) stored in HVAC/Body module.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
Similar codes
Repair manuals
Brands with available manuals
2,970
The library contains 2,970 repair and diagnostic manuals. Choose a brand to open the full manual tree by year, model and trim.
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