Code
B1C29
MITSUBISHI
B — Body
Left side ABG squib open
Views:
UK: 17
EN: 28
RU: 23
AI status
Completed
Completed
100%
Causes
- Open (broken) wiring in left airbag squib circuit
- Disconnected or corroded connector at squib or seat harness
- Faulty left-side airbag squib (seat/side airbag module)
- Faulty airbag ECU/diagnostic unit or internal connector
- Poor connection at seat wiring harness/quick connector or floor harness
- Damage to wiring from seat adjustment, bolts, or previous repairs
Symptoms
- SRS/Airbag warning light ON
- Possible disablement of left-side airbag deployment for crash events
- Stored DTC B1C29 (and possibly related SRS codes)
- No other obvious drivability symptoms (vehicle may otherwise run normally)
What to check
- With scan tool, read SRS system codes and freeze frames; confirm B1C29 present
- Visually inspect left seat/door side airbag connectors and harness routing for damage or disconnected plugs
- Verify SRS disable procedure before touching components (follow manufacturer procedure to disable airbags)
- Check connector pins for corrosion, bending, or pushed-out terminals at squib and ECU connectors
- Perform a continuity/resistance check of the left squib circuit from ECU connector to squib connector (with battery disconnected and SRS disabled)
- Wiggle test harness/connectors while monitoring resistance or live data to reproduce intermittent opens
Signal parameters
- Typical intact squib resistance: low ohms (commonly around 1–6 Ω depending on squib design)
- Open-circuit reading: infinite/OL or very high resistance (>>1000 Ω)
- Short-to-ground or short-to-power would show very low resistance or near 0 Ω (different DTC)
- ECU monitors continuity; open condition reported when circuit resistance exceeds manufacturer threshold
Diagnostic algorithm
- Safety first: follow the manufacturer’s SRS disable procedure before any inspection or testing (disconnect battery and wait per workshop manual)
- Connect a compatible SRS diagnostic scanner and confirm B1C29 and any related codes; note freeze frame and event data
- Visually inspect the left-side airbag (seat/door) connector, wiring, and harness routing for damage, corrosion, or disconnection
- With SRS disabled, measure resistance between the squib connector terminals. Compare to expected range in service manual. An open (OL) indicates broken/disconnected wiring or failed squib
- If open, trace wiring toward the ECU: perform continuity checks section-by-section to locate break or connector fault; repair any broken wires or poor terminations
- If continuity from ECU to squib is good, but resistance is out of specification, replace the left-side squib (airbag module) per manufacturer instructions
- After repairs, reconnect SRS, clear DTCs with scan tool, cycle ignition, and verify codes do not return; perform final system check per manufacturer procedure
- If fault persists after wiring and squib verified good, suspect airbag ECU fault or intermittent connector—inspect/replace ECU or consult manufacturer service information
Likely causes
- Disconnected or corroded connector at left side squib
- Broken wire in seat harness (common where seat belt/seat moves)
- Faulty left-side squib (airbag module)
Fault status
Status
B1C29 — Left-side ABG (airbag) squib open: open circuit detected in the left-side airbag deployment circuit. SRS warning lamp illuminated; left-side airbag may be disabled until fault is corrected.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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