Code
B2707
HUMMER
B — Body
Passenger occupant detection sensor circuit short to battery
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring harness under the passenger seat contacting battery voltage
- Corroded or loose connector pins at the occupant detection sensor or SRS control module
- Moisture/water intrusion in the seat or connector (causing unintended conductive path to battery)
- Faulty passenger occupant detection sensor (seat mat/module) internally shorted
- Aftermarket seat heaters, seat covers, or repairs that altered sensor wiring or introduced shortcuts
- Faulty SRS/occupant classification control module or internal driver circuitry
Symptoms
- SRS/Airbag warning lamp illuminated on instrument cluster
- Passenger airbag ON/OFF indicator may be incorrect or show “check”/disabled
- Possible DIC message about passenger airbag system
- Passenger occupant detection not detecting occupant correctly (false enable/disable)
- Some vehicles may disable the passenger airbag until the fault is cleared
What to check
- Read and record stored freeze-frame and related SRS codes with a capable scan tool
- Visually inspect passenger seat, seat tracks, connectors and harness for damage, corrosion, or contamination
- Check under-seat area for aftermarket devices (seat heaters, alarms) or water entry
- With ignition ON (engine off) backprobe the occupant sensor signal circuit and compare to battery voltage — look for constant B+ on the sensor circuit
- Perform a wiggle test while watching live data; look for change in signal or new codes
- Inspect connector terminals for pushed-out pins or signs of arcing
Signal parameters
- Normal: a variable low-level sensor signal reported to the occupant classification module (not a constant battery voltage)
- Fault condition: sensor circuit reads constant battery voltage (~vehicle B+) when probed with ignition ON indicating a short to battery
- Expected behaviour after repair: signal returns to varying/nominal values and code does not reappear
Diagnostic algorithm
- Retrieve B2707 and related codes and record freeze frame and live data. Do not perform repairs without following SRS safety procedures.
- Follow OEM SRS service safety: disable battery negative terminal and wait the specified time before disconnecting any airbag/occupant sensor connectors.
- Visually inspect passenger seat, harness, and connectors for damage, corrosion, contamination, or aftermarket mods. Pay attention to seat track pinch points and seat heater retrofits.
- Reconnect battery per safety rules for live testing or use an isolated power method per OEM. With a capable scan tool, monitor occupant detection sensor live data and backprobe the sensor connector with ignition ON. If the circuit reads constant battery voltage, suspect a short to B+.
- With key off, measure resistance/continuity between the sensor signal circuit and battery positive. Low resistance indicates a short; high resistance/open is expected.
- Unplug the occupant sensor connector at the seat. If the module end no longer reads B+ on the circuit, the short is in the seat harness/sensor. If it still reads B+, trace harness back to SRS module for pin/connector faults.
- If wiring is damaged, repair or replace the harness using correct gauge wire and OEM splice methods. If the sensor mat is faulty, replace the occupant detection sensor/mat assembly.
- After repair, clear codes, perform required occupant classification system initialization/calibration per OEM, and verify no reoccurrence during test drive and multiple ignition cycles.
- If wiring and sensor check good but fault persists, test/replace SRS/occupant classification control module per OEM diagnostic flow.
- Document repair and retest to confirm proper passenger airbag status indications.
Likely causes
- Wiring rubbed through at seat track and contacting a B+ feed
- Connector pin pushed into housing contacting B+ pin or terminal
- Seat cushion moisture bridging sensor traces to B+
- Failed sensor mat with internal short to battery
Fault status
Status
Passenger occupant detection sensor circuit short to battery — sensor circuit voltage tied to battery positive causing occupant classification fault; SRS/airbag warning and passenger airbag status may be affected.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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