Code
B0042
HUMMER
B — Body
Left Front/Driver Frontal Deployment Loop Circuit
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in the left front/frontal squib circuit
- Poor or corroded connector(s) at the squib, airbag module, or intermediate components
- Faulty left front airbag (squib) or seat harness connection
- Faulty clock spring (steering wheel slip ring) if circuit routes through steering column
- Faulty or damaged airbag control module (ACM) or its connector
- Previous deployment damage or improper repair to SRS wiring
Symptoms
- SRS/airbag warning light illuminated on dash
- Possible loss of airbag deployment for left front/driver frontal position
- Diagnostic trouble code B0042 stored in airbag control module
- Intermittent SRS light that may change with steering or seat movement
- Related faults or multiple airbag DTCs present
What to check
- Retrieve and record all stored SRS codes with a capable scan tool
- Visually inspect left front airbag connector, harness, and routing for damage
- Check steering wheel/clock spring condition and connector seating if circuit passes through steering column
- Check connectors at the airbag module and passenger compartment for corrosion or loose pins
- Verify vehicle battery condition and system voltage prior to testing
- Confirm proper post-repair clearance of codes using scan tool and perform self-tests
Signal parameters
- Expected squib resistance (typical low-ohm range) — measure across the squib terminals with service manual reference values
- Open-circuit: infinite/OL on ohmmeter between squib terminals
- Short to ground or battery: near 0 ohms between squib terminal and chassis ground or B+ respectively
- ACM connector pin voltages: reference values per service manual when key on
- Continuity expected between module pin and airbag connector when harness intact
Diagnostic algorithm
- Read and record all SRS codes with an OEM-capable scan tool and note freeze frame data.
- Follow safety procedures: disable SRS power (disconnect battery) and wait the manufacturer-specified time before touching airbag components. Consult the service manual for exact intervals.
- Perform a careful visual inspection of the left front airbag, connector, and wiring harness routing (look for chafing, pinched wires, corrosion, or heat damage).
- With battery disconnected and following safety hold times, disconnect the left front airbag connector and measure squib resistance at the airbag side. Compare to OEM specification (low-ohm value).
- Measure resistance/continuity from the airbag module squib pin to the airbag connector pin to check for open circuit or high resistance. Wiggle harness during test to identify intermittent faults.
- Check for shorts: measure resistance from each squib wire to chassis ground and to battery positive to detect short to ground or B+.
- Inspect and test the clock spring if the circuit runs through the steering column (verify continuity and absence of high resistance between module and airbag connector pins).
- Inspect module connectors for bent pins, corrosion, or damage; perform pin-back probe voltage checks per service manual with ignition on (if allowed by manual) to verify driver module outputs.
- Repair or replace damaged wiring, connectors, clock spring, or airbag assembly as indicated by test results. Replace components using OEM parts and follow torque and connector engagement procedures.
- After repairs, reconnect battery, clear codes with scan tool, and perform SRS system self-test and a road/test verification as required by manufacturer.
- Note: Always follow the vehicle manufacturer's SRS service procedures and safety steps. If unsure, refer to the factory service manual or qualified SRS technician.
Likely causes
- Broken wire or pinched conductor in driver frontal squib harness near the door hinge, seat, or steering column
- Loose, corroded, or pushed-out pin in squib connector at the airbag assembly or module
- High resistance at connector due to corrosion/contamination
- Clock spring failure (if left frontal squib wiring passes through steering column)
- Damaged airbag module or internal squib short/failure
Fault status
Status
Left front (driver) frontal deployment loop circuit fault detected — open, short, or high resistance in the driver frontal airbag circuit.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
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