Code
B0066
HUMMER
B — Body
Occupant Restraint System Circuit Fault
Views:
UK: 14
EN: 28
RU: 16
AI status
Completed
Completed
100%
Causes
- Open or short in airbag/pretensioner squib circuit
- Faulty clock spring (driver airbag)
- Loose, corroded or damaged connector (under seat or in dash)
- Faulty Occupant Restraint Sensing and Diagnostic Module (SDM) or Body Control Module (BCM)
- Water intrusion or physical damage to wiring harness
- Low or intermittent vehicle battery/voltage supply to SRS module
Symptoms
- Airbag warning lamp ON (steady or flashing)
- Seat belt warning lamp or chime may be active
- Occupant restraint system disabled or partial disablement
- Intermittent fault codes or recurring code after clearing
- Possible inability of affected restraint devices to deploy in a crash
What to check
- Read and record all SRS-related codes and freeze frame with a capable scan tool
- Verify vehicle battery voltage and grounds; ensure stable 12V supply
- Visually inspect connectors under seats, in door jambs, and at the steering column
- Check for signs of water intrusion, corrosion, or physical damage to harness
- Perform continuity and resistance checks on squib and pretensioner circuits per manufacturer procedure
- Wiggle-test harnesses while monitoring live data or DTC status (use caution)
Signal parameters
- SRS module supply voltage: nominal battery voltage (~12V) when key on
- Squib/pretensioner circuit resistance: typically low (a few ohms) when intact; open circuit indicates high or infinite resistance
- An open circuit or very high resistance often registers as OL/— on an ohmmeter
- Short to power reads near battery voltage on circuit pin; short to ground reads near 0V (measure only with proper safety procedures)
- Diagnostic tool may show status bits for each squib/seat occupancy sensor and sensor fault flags
Diagnostic algorithm
- Record all SRS codes and freeze frame data with an OEM-capable scan tool. Note history vs active status.
- Restore vehicle to safe state: disable battery per manufacturer instructions (disconnect negative terminal and wait required time) before probing squib connectors.
- Visually inspect wiring and connectors for damage, corrosion, or water. Repair or secure as needed.
- Reconnect battery per procedure and verify stable supply to SDM; re-scan for codes. If code returns, proceed.
- Use a diagnostic tool to monitor SRS live data while carefully performing wiggle tests on wiring and connectors (avoid sharp pulls and possible deployment).
- With power removed and following manufacturer safety steps, measure resistance/continuity of suspect squib/pretensioner circuits and clock spring circuit. Compare to service limits.
- If an open/short is found, trace and repair wiring (splice, replace harness, repair connector). After repair, clear codes and verify no recurrence.
- If wiring and connectors are good but resistance values indicate a failed module or airbag assembly, replace only the failed component (airbag, pretensioner, or SDM) following manufacturer replacement and calibration procedures.
- After repairs, perform SRS system reset/clear with scan tool and verify readiness; confirm no stored/active faults and correct indicators.
- If module replacement required, follow proper disposal, replacement, and initialization (programming/pairing) instructions.
Likely causes
- Disconnected or corroded connector at seat, door, or steering column
- Broken wiring where harness flexes (seat position, door jamb, steering column)
- Failed clock spring causing open/short to driver airbag
- Faulty airbag module or pretensioner with incorrect squib resistance
- SDM internal fault or intermittent power/ground
Fault status
Status
Occupant Restraint System Circuit Fault — electrical fault detected in airbag/pretensioner circuits or related sensors/modules. Investigate wiring, connectors, clock spring, squibs, and SRS module.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 Hours
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