Code
B0042
Generic
B — Body
Third Row Left Frontal Stage 2 Deployment Control
AI status
Completed
Completed
100%
Causes
- Open or short in the Stage 2 squib (airbag) wiring
- High resistance in the squib circuit (connector corrosion, damaged conductor)
- Faulty third-row left frontal airbag (squib) assembly
- Loose, corroded, or disconnected connector at the airbag or SRS module
- Damage to wiring from prior repairs or impact (pinched/cut/chafed harness)
- Short to ground or to battery positive on the deployment circuit
Symptoms
- SRS / airbag warning light illuminated on dash
- DTC B0042 stored in airbag control module
- Possible disablement of related restraint functions (seatbelt pretensioners or other stages)
- No obvious mechanical symptoms until a crash event
- Multiple related SRS DTCs present in some cases
What to check
- Retrieve SRS codes and freeze frame data with a qualified scan tool
- Verify vehicle battery voltage and charge state before testing
- Visually inspect third-row left frontal airbag connector and harness for damage, corrosion, or water intrusion
- Check for signs of prior collision repair in the area of the third row
- Inspect related connectors at the SRS control module
- Measure continuity and resistance of the Stage 2 squib circuit (follow manufacturer safety procedures)
Signal parameters
- Squib resistance: typically low (single-digit ohms). Compare to vehicle-specific spec before replacing components.
- Normal circuit: continuity present, no short to chassis or battery positive when system is armed
- Firing event: high-current pulse is commanded by the SRS module only during deployment (do not attempt to replicate)
- Diagnostic signals available via SRS scan tool: squib resistance/line status and module output driver status
Diagnostic algorithm
- Read and record all SRS codes and freeze frame data with a capable scan tool. Note any other related codes.
- Verify good battery condition and restore to nominal voltage if low. Disable vehicle power per manufacturer procedure before handling SRS circuits.
- Visually inspect the third-row left frontal airbag connector, pigtail, and harness for corrosion, bent pins, damage, or water ingress. Repair/replace damaged connectors.
- With the airbag system disabled per safety procedure, measure squib resistance (ohms) at the connector. Compare to manufacturer spec. An open or very high resistance indicates an open circuit; a short or near-zero to-chassis indicates a short.
- Check continuity from the squib connector to the SRS module connector. Inspect for shorts to ground or battery positive.
- Perform wiggle and flex testing of the harness while monitoring resistance or live data to detect intermittent faults.
- If resistance and continuity are within spec but the code remains, inspect and test the SRS control module outputs and grounds for proper operation. Replace module only if confirmed faulty and follow immobilization/initialization procedures.
- Replace faulty squib/airbag or repair wiring/connectors as required. Always use manufacturer-approved replacement parts and follow proper handling and disposal for airbag components.
- After repairs, clear codes, perform SRS system self-tests with a scan tool, and confirm no reoccurrence. Document repairs and ensure system readiness.
Likely causes
- Corroded/loose connector at the third-row left frontal squib
- Open circuit in the squib wiring (broken conductor or connector)
- Short to ground in the deployment lead (insulation damage)
- Defective squib (internal short or open)
- SRS module output driver failure
Fault status
Status
SRS fault — Third Row Left Frontal Stage 2 deployment control circuit: open/short/high resistance detected. Airbag warning lamp active; deployment function may be impaired.
Repair difficulty: Hard
Diagnostic time: 1.0 - 3.5 hours
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Code
B0042
HUMMER
B — Body
Left Front/Driver Frontal Deployment Loop Circuit
AI status
Completed
Completed
100%
Causes
- Open or short in the Stage 2 squib (airbag) wiring
- High resistance in the squib circuit (connector corrosion, damaged conductor)
- Faulty third-row left frontal airbag (squib) assembly
- Loose, corroded, or disconnected connector at the airbag or SRS module
- Damage to wiring from prior repairs or impact (pinched/cut/chafed harness)
- Short to ground or to battery positive on the deployment circuit
Symptoms
- SRS / airbag warning light illuminated on dash
- DTC B0042 stored in airbag control module
- Possible disablement of related restraint functions (seatbelt pretensioners or other stages)
- No obvious mechanical symptoms until a crash event
- Multiple related SRS DTCs present in some cases
What to check
- Retrieve SRS codes and freeze frame data with a qualified scan tool
- Verify vehicle battery voltage and charge state before testing
- Visually inspect third-row left frontal airbag connector and harness for damage, corrosion, or water intrusion
- Check for signs of prior collision repair in the area of the third row
- Inspect related connectors at the SRS control module
- Measure continuity and resistance of the Stage 2 squib circuit (follow manufacturer safety procedures)
Signal parameters
- Squib resistance: typically low (single-digit ohms). Compare to vehicle-specific spec before replacing components.
- Normal circuit: continuity present, no short to chassis or battery positive when system is armed
- Firing event: high-current pulse is commanded by the SRS module only during deployment (do not attempt to replicate)
- Diagnostic signals available via SRS scan tool: squib resistance/line status and module output driver status
Diagnostic algorithm
- Read and record all SRS codes and freeze frame data with a capable scan tool. Note any other related codes.
- Verify good battery condition and restore to nominal voltage if low. Disable vehicle power per manufacturer procedure before handling SRS circuits.
- Visually inspect the third-row left frontal airbag connector, pigtail, and harness for corrosion, bent pins, damage, or water ingress. Repair/replace damaged connectors.
- With the airbag system disabled per safety procedure, measure squib resistance (ohms) at the connector. Compare to manufacturer spec. An open or very high resistance indicates an open circuit; a short or near-zero to-chassis indicates a short.
- Check continuity from the squib connector to the SRS module connector. Inspect for shorts to ground or battery positive.
- Perform wiggle and flex testing of the harness while monitoring resistance or live data to detect intermittent faults.
- If resistance and continuity are within spec but the code remains, inspect and test the SRS control module outputs and grounds for proper operation. Replace module only if confirmed faulty and follow immobilization/initialization procedures.
- Replace faulty squib/airbag or repair wiring/connectors as required. Always use manufacturer-approved replacement parts and follow proper handling and disposal for airbag components.
- After repairs, clear codes, perform SRS system self-tests with a scan tool, and confirm no reoccurrence. Document repairs and ensure system readiness.
Likely causes
- Corroded/loose connector at the third-row left frontal squib
- Open circuit in the squib wiring (broken conductor or connector)
- Short to ground in the deployment lead (insulation damage)
- Defective squib (internal short or open)
- SRS module output driver failure
Fault status
Status
SRS fault — Third Row Left Frontal Stage 2 deployment control circuit: open/short/high resistance detected. Airbag warning lamp active; deployment function may be impaired.
Repair difficulty: Hard
Diagnostic time: 1.0 - 3.5 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
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