Code
B0104
Generic
B — Body
Sensor Cleaning Air Blower Actuator A Control Relay
Views:
UK: 20
EN: 29
RU: 27
AI status
Completed
Completed
100%
Causes
- Blown fuse supplying the relay or blower circuit
- Failed control relay (stuck contacts or open coil)
- Open, shorted or high-resistance wiring between module, relay, and blower actuator
- Corroded/loose relay socket or connector terminals
- Blower actuator (motor/transistor pack) internal fault or mechanical binding
- Faulty body control module / sensor-cleaning system module or poor ground
Symptoms
- Sensor cleaning blower does not operate when commanded
- Intermittent or no operation of blower during sensor-clean cycle
- Blower runs continuously or cannot be turned off (stuck relay)
- DTC B0104 stored and may reappear after clearing
- Blown fuse when attempting to operate the blower
What to check
- Read and record freeze-frame and related codes; clear code and attempt a re-test
- Visual inspection of relay, relay socket, associated fuses and wiring for damage or corrosion
- Verify fuse continuity and correct fuse value
- Swap relay with identical known-good relay (if available) to confirm relay behavior
- Backprobe relay coil and switched terminals while commanding the blower to observe control and switched voltages
- Measure blower actuator resistance and check for free rotation or mechanical binding
Signal parameters
- Relay coil resistance (typical): ~50–200 ohms (manufacturer-specific — check service data)
- Control signal to relay coil: approx. 0 V (off) / battery voltage (~11–14.5 V) (on)
- Switched output to blower actuator: battery voltage (approx. 11–14.5 V) when relay closed
- Blower actuator current draw: small blower motors typically ~0.5–5 A depending on design—significantly higher values indicate a jam or short
- Ground continuity: chassis ground for relay/actuator should be near 0 ohms to battery negative
Diagnostic algorithm
- Retrieve stored codes and freeze-frame data. Note conditions when fault set.
- Attempt to operate the sensor-clean blower while observing whether the relay clicks. If no click, remove relay and inspect socket/fuse.
- Check related fuse(s) for continuity and correct rating. Replace fuse only after diagnosing root cause if repeatedly blown.
- Swap the relay with a known-good, identical relay to quickly confirm/clear relay failure.
- With ignition on and system commanded, backprobe the relay coil terminals: verify control voltage to coil and ground return. If control voltage never appears, test module output and wiring to the module.
- Backprobe the relay switched terminal and measure voltage to the blower actuator while commanded. If voltage present but blower not running, test blower motor directly with fused bench supply and verify current draw/rotation.
- Inspect and measure continuity of wiring between relay, blower actuator, and module; repair any open or high-resistance connections. Check for pin corrosion, broken wires, or chafing.
- If actuator draws excessive current during bench test or stalls, repair or replace the blower actuator assembly.
- If wiring, relay and actuator test good but control signal from the module is missing or incorrect, inspect module grounds and supply voltages. Replace/repair module only after confirming external components/wiring are good.
- Clear codes and perform operational test cycles to confirm repair. Re-scan to ensure code does not return.
Likely causes
- Failed control relay
- Blown fuse or poor fuse connection
- Open/short in wiring or corroded connector at relay or actuator
- Blower actuator drawing excessive current (mechanical jam or short)
Fault status
Status
Sensor Cleaning Air Blower Actuator A control relay circuit malfunction — possible open/short/relay failure or actuator draw issue.
Repair difficulty: Medium
Diagnostic time: 0.5-2 hours
Similar codes
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Code
B0104
HUMMER
B — Body
Electronic Frontal Sensor Circuit
Views:
UK: 16
EN: 28
RU: 19
AI status
Completed
Completed
100%
Causes
- Blown fuse supplying the relay or blower circuit
- Failed control relay (stuck contacts or open coil)
- Open, shorted or high-resistance wiring between module, relay, and blower actuator
- Corroded/loose relay socket or connector terminals
- Blower actuator (motor/transistor pack) internal fault or mechanical binding
- Faulty body control module / sensor-cleaning system module or poor ground
Symptoms
- Sensor cleaning blower does not operate when commanded
- Intermittent or no operation of blower during sensor-clean cycle
- Blower runs continuously or cannot be turned off (stuck relay)
- DTC B0104 stored and may reappear after clearing
- Blown fuse when attempting to operate the blower
What to check
- Read and record freeze-frame and related codes; clear code and attempt a re-test
- Visual inspection of relay, relay socket, associated fuses and wiring for damage or corrosion
- Verify fuse continuity and correct fuse value
- Swap relay with identical known-good relay (if available) to confirm relay behavior
- Backprobe relay coil and switched terminals while commanding the blower to observe control and switched voltages
- Measure blower actuator resistance and check for free rotation or mechanical binding
Signal parameters
- Relay coil resistance (typical): ~50–200 ohms (manufacturer-specific — check service data)
- Control signal to relay coil: approx. 0 V (off) / battery voltage (~11–14.5 V) (on)
- Switched output to blower actuator: battery voltage (approx. 11–14.5 V) when relay closed
- Blower actuator current draw: small blower motors typically ~0.5–5 A depending on design—significantly higher values indicate a jam or short
- Ground continuity: chassis ground for relay/actuator should be near 0 ohms to battery negative
Diagnostic algorithm
- Retrieve stored codes and freeze-frame data. Note conditions when fault set.
- Attempt to operate the sensor-clean blower while observing whether the relay clicks. If no click, remove relay and inspect socket/fuse.
- Check related fuse(s) for continuity and correct rating. Replace fuse only after diagnosing root cause if repeatedly blown.
- Swap the relay with a known-good, identical relay to quickly confirm/clear relay failure.
- With ignition on and system commanded, backprobe the relay coil terminals: verify control voltage to coil and ground return. If control voltage never appears, test module output and wiring to the module.
- Backprobe the relay switched terminal and measure voltage to the blower actuator while commanded. If voltage present but blower not running, test blower motor directly with fused bench supply and verify current draw/rotation.
- Inspect and measure continuity of wiring between relay, blower actuator, and module; repair any open or high-resistance connections. Check for pin corrosion, broken wires, or chafing.
- If actuator draws excessive current during bench test or stalls, repair or replace the blower actuator assembly.
- If wiring, relay and actuator test good but control signal from the module is missing or incorrect, inspect module grounds and supply voltages. Replace/repair module only after confirming external components/wiring are good.
- Clear codes and perform operational test cycles to confirm repair. Re-scan to ensure code does not return.
Likely causes
- Failed control relay
- Blown fuse or poor fuse connection
- Open/short in wiring or corroded connector at relay or actuator
- Blower actuator drawing excessive current (mechanical jam or short)
Fault status
Status
Sensor Cleaning Air Blower Actuator A control relay circuit malfunction — possible open/short/relay failure or actuator draw issue.
Repair difficulty: Medium
Diagnostic time: 0.5-2 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
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