Code
B0077
Generic
B — Body
Third Row Center Seat Belt Pretensioner Deployment Control
AI status
Completed
Completed
100%
Causes
- Open or short in pretensioner wiring (open circuit, short to ground or battery)
- Corroded, loose, damaged or disconnected connector at the third‑row center pretensioner
- Failed or previously deployed pretensioner squib
- Faulty SRS / airbag control module or driver for the squib circuit
- Water intrusion or physical damage to seat wiring harness
- Incorrect or incomplete repairs after a collision (improperly repaired harness or connectors)
Symptoms
- SRS / airbag warning lamp or 'Service Airbag' message illuminated
- Related pretensioner may not arm or may be disabled in system diagnostics
- Possible diagnostic trouble codes stored for other SRS components
- Failure to clear the B0077 code until root cause repaired
- After a crash, pretensioner did not deploy or system recorded an incomplete deployment
What to check
- Use an OBD2 scan tool with SRS capability to read B0077 and any related SRS codes and freeze frame data
- Inspect third‑row center seat and connector for damage, corrosion, water intrusion or loose pins
- Visually inspect entire pretensioner wiring route for chafing, cuts, or pinch points
- Verify SRS control module power and ground circuits are within specification
- Measure continuity and resistance of the pretensioner squib with the connector disconnected (compare to manufacturer spec)
- Check for short to ground or short to battery on the pretensioner wiring harness
Signal parameters
- Typical pretensioner squib resistance: low ohms range (commonly ~0.5–3.0 Ω) — consult vehicle spec
- Open circuit: very high or infinite resistance (indicates open wiring or disconnected squib)
- Short to ground or battery: near 0 Ω or unexpected continuity to chassis/battery
- At rest (no deployment command): no sustained battery voltage should be present on the squib wiring
- When commanded (module fires squib): brief high‑current pulse from module (battery voltage present only during the pulse) — handled only by module during deployment
Diagnostic algorithm
- Safety first: follow manufacturer SRS safety procedures before any work (disable battery per spec and wait required time).
- Connect a capable scan tool, read and record B0077 plus any other SRS codes and freeze frame data. Note any crash data or deployment history.
- Visually inspect the third‑row center pretensioner connector, seat harness, and routing for damage, corrosion, pin push‑out or water intrusion. Repair any physical damage.
- With battery disabled and connector unplugged, measure squib resistance across the pretensioner terminals. Compare to manufacturer specification. Replace pretensioner if resistance is out of spec or indicates prior deployment.
- Check continuity from the pretensioner connector back to the SRS module pins. Inspect for intermittent opens by gently manipulating the harness while monitoring continuity.
- Check for shorts to chassis ground or to battery on the pretensioner wires (between each squib conductor and ground/battery). Repair wiring insulation or replace harness as needed.
- Verify SRS module power, ground and communications. If wiring to module is good but the module shows driver faults for that circuit, consider module diagnosis or replacement per manufacturer procedure.
- After repairs, clear codes, reconnect battery per safety procedure, and run SRS system tests with scan tool. Confirm B0077 does not return and perform any required system initialization or seat/pretensioner pairing if applicable.
- If code persists after wiring and pretensioner replacement, follow manufacturer advanced diagnostics which may include bench testing the module or contacting technical support.
Likely causes
- Short-to-ground on the pretensioner driver circuit due to chafed harness at seat or floor area
- Corroded or pushed‑out pin in the pretensioner connector at the seat
- Pretensioner already deployed (internal short/low resistance) or internal open (high resistance) in the squib
- Poor ground or supply to the SRS control module affecting deployment circuit monitoring
- SRS control module fault or blown driver transistor in the module
Fault status
Status
B0077 — Fault detected in third‑row center seat belt pretensioner deployment control circuit. The SRS control module has identified abnormal circuit behavior (open, short, high resistance or driver fault). This will illuminate the SRS warning and may disable the related pretensioner until the fault is corrected. Inspect wiring, connector, pretensioner and SRS module as appropriate.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Code
B0077
HUMMER
B — Body
Left Front/Driver Side Impact Sensor (SIS) Malfunction
AI status
Completed
Completed
100%
Causes
- Open or short in pretensioner wiring (open circuit, short to ground or battery)
- Corroded, loose, damaged or disconnected connector at the third‑row center pretensioner
- Failed or previously deployed pretensioner squib
- Faulty SRS / airbag control module or driver for the squib circuit
- Water intrusion or physical damage to seat wiring harness
- Incorrect or incomplete repairs after a collision (improperly repaired harness or connectors)
Symptoms
- SRS / airbag warning lamp or 'Service Airbag' message illuminated
- Related pretensioner may not arm or may be disabled in system diagnostics
- Possible diagnostic trouble codes stored for other SRS components
- Failure to clear the B0077 code until root cause repaired
- After a crash, pretensioner did not deploy or system recorded an incomplete deployment
What to check
- Use an OBD2 scan tool with SRS capability to read B0077 and any related SRS codes and freeze frame data
- Inspect third‑row center seat and connector for damage, corrosion, water intrusion or loose pins
- Visually inspect entire pretensioner wiring route for chafing, cuts, or pinch points
- Verify SRS control module power and ground circuits are within specification
- Measure continuity and resistance of the pretensioner squib with the connector disconnected (compare to manufacturer spec)
- Check for short to ground or short to battery on the pretensioner wiring harness
Signal parameters
- Typical pretensioner squib resistance: low ohms range (commonly ~0.5–3.0 Ω) — consult vehicle spec
- Open circuit: very high or infinite resistance (indicates open wiring or disconnected squib)
- Short to ground or battery: near 0 Ω or unexpected continuity to chassis/battery
- At rest (no deployment command): no sustained battery voltage should be present on the squib wiring
- When commanded (module fires squib): brief high‑current pulse from module (battery voltage present only during the pulse) — handled only by module during deployment
Diagnostic algorithm
- Safety first: follow manufacturer SRS safety procedures before any work (disable battery per spec and wait required time).
- Connect a capable scan tool, read and record B0077 plus any other SRS codes and freeze frame data. Note any crash data or deployment history.
- Visually inspect the third‑row center pretensioner connector, seat harness, and routing for damage, corrosion, pin push‑out or water intrusion. Repair any physical damage.
- With battery disabled and connector unplugged, measure squib resistance across the pretensioner terminals. Compare to manufacturer specification. Replace pretensioner if resistance is out of spec or indicates prior deployment.
- Check continuity from the pretensioner connector back to the SRS module pins. Inspect for intermittent opens by gently manipulating the harness while monitoring continuity.
- Check for shorts to chassis ground or to battery on the pretensioner wires (between each squib conductor and ground/battery). Repair wiring insulation or replace harness as needed.
- Verify SRS module power, ground and communications. If wiring to module is good but the module shows driver faults for that circuit, consider module diagnosis or replacement per manufacturer procedure.
- After repairs, clear codes, reconnect battery per safety procedure, and run SRS system tests with scan tool. Confirm B0077 does not return and perform any required system initialization or seat/pretensioner pairing if applicable.
- If code persists after wiring and pretensioner replacement, follow manufacturer advanced diagnostics which may include bench testing the module or contacting technical support.
Likely causes
- Short-to-ground on the pretensioner driver circuit due to chafed harness at seat or floor area
- Corroded or pushed‑out pin in the pretensioner connector at the seat
- Pretensioner already deployed (internal short/low resistance) or internal open (high resistance) in the squib
- Poor ground or supply to the SRS control module affecting deployment circuit monitoring
- SRS control module fault or blown driver transistor in the module
Fault status
Status
B0077 — Fault detected in third‑row center seat belt pretensioner deployment control circuit. The SRS control module has identified abnormal circuit behavior (open, short, high resistance or driver fault). This will illuminate the SRS warning and may disable the related pretensioner until the fault is corrected. Inspect wiring, connector, pretensioner and SRS module as appropriate.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
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