Code
B1134
HUMMER
B — Body
Front Passenger Occupant Classification Sensor Circuit Fault
AI status
Completed
Completed
100%
Causes
- Open or short in occupant classification sensor wiring harness
- Corroded or loose connector at sensor or RCM
- Failed occupant classification sensor module (seat mat)
- Water/moisture or debris intrusion under the seat
- Poor ground or power supply to the sensor circuit
- Improper seat reassembly, aftermarket seat covers or mats interfering with sensor
Symptoms
- SRS/airbag warning lamp illuminated
- Passenger airbag status may be disabled or incorrectly displayed
- Passenger airbag indicator (OFF/ON) behavior inconsistent or stuck
- Diagnostic trouble codes related to occupant classification stored in RCM
- Possible inability to complete occupant classification system calibration
What to check
- Read DTCs and freeze frame data with an SRS-capable scan tool; record all occupant-related codes
- Visually inspect passenger seat, connectors and wiring harness under the seat for damage, pin corrosion, or water/moisture
- Check for aftermarket seat covers, cushions or objects that could interfere with the sensor mat
- Wiggle test wiring while watching live data/scan tool for intermittent changes
- Backprobe the sensor connector to measure reference voltage, signal and ground with ignition on (follow safety procedures)
- Check continuity and resistance of harness between sensor connector and RCM with battery disconnected
Signal parameters
- Reference/supply voltage: typically a regulated 5 V reference from RCM (verify OEM spec)
- Signal voltage: varies with load/occupant, generally within 0–5 V range depending on system design
- Expected circuit behavior: no open circuit and no short to battery or ground; intermittent fluctuations indicate wiring/connectivity problem
- Common fault types reported by the RCM: open circuit, short to ground, short to battery/ignition, high resistance/intermittent
Diagnostic algorithm
- Read and record all SRS/occupant classification DTCs and freeze frame data using an SRS-qualified scan tool.
- Follow vehicle-specific SRS safety procedures: disable SRS power (battery disconnect) before accessing connectors or performing repairs.
- Visually inspect passenger seat, sensor mat area, connectors and harness routing for damage, chafing, moisture or foreign objects; remove aftermarket covers/cushions and re-test.
- Reconnect battery/power (if disconnected) and backprobe the sensor connector with the ignition ON (do not deploy) to verify reference voltage, signal and ground according to OEM specs.
- If no proper voltages, disconnect sensor and check harness continuity and for short to ground or battery between the sensor connector and RCM with battery disconnected.
- Repair any damaged wiring, terminals, or connectors (replace connector pins, harness sections, or sensor as required). Use corrosion-resistant replacements and proper seals.
- Replace occupant classification sensor module if wiring and connectors test good and symptoms persist.
- After repairs, clear codes and perform required occupant classification/RCM calibration or learning procedure with a scan tool per manufacturer instructions.
- Verify proper system operation: no SRS lamp, correct passenger airbag status, and no reappearance of B1134 after test drive.
Likely causes
- Damaged wiring or connector under the passenger seat (most common)
- Corrosion or contamination at the sensor or connector pins
- Sensor module failure in the passenger seat mat
- Improperly installed seat cover or object on seat affecting the mat
- Intermittent open/short caused by seat movement
Fault status
Status
Stored when the front passenger occupant classification sensor circuit is detected as open, shorted or intermittent by the restraint control module. The condition can disable or alter passenger airbag status and will illuminate the SRS warning lamp until repaired and cleared.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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