Code
B1403
MITSUBISHI
B — Body
F ABG(1)DR.squib short to BATT.
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UK: 6
EN: 19
RU: 12
AI status
Completed
Completed
100%
Causes
- Damaged wiring insulation or chafing in the driver airbag squib circuit allowing contact with constant battery feed
- Faulty or corroded connector (pin pushed out, bent pin, water intrusion) at squib or SRS ECU
- Shorted clock spring (spiral cable) in the steering column
- Faulty airbag squib (internal short in the airbag/seatbelt pretensioner device)
- Incorrect or damaged aftermarket accessories tied into wiring harness
- Faulty SRS control module or internal driver pin short
Symptoms
- SRS/airbag warning lamp illuminated continuously
- Possible loss of airbag deployment for the affected circuit (module may disable system)
- DTC B1403 stored in SRS memory and may persist after key cycles
- Possibly related faults for other airbag circuits or steering wheel controls
What to check
- Safety first: disable SRS power by disconnecting negative battery terminal and wait manufacturer-specified time before touching SRS components
- Use a scan tool to read SRS codes and freeze frame data; record related codes
- Visual inspection of wiring and connectors from SRS ECU to driver airbag/clock spring for damage, burnt insulation, corrosion or aftermarket splices
- Disconnect the driver squib connector (or clock spring connector) and check for presence of battery voltage on the squib circuit with ignition ON (use insulated probes)
- Measure squib/clock spring resistance with battery disconnected — compare to spec and look for near-zero indicating short or very high/open indicating open circuit
- Back-probe connectors to isolate whether short is at connector, in clock spring, or downstream to the squib
Signal parameters
- Expected squib resistance (typical range): about 1–5 ohms (vehicle-specific — consult service manual). A very low resistance (near 0 ohms) can indicate a short; very high/infinite indicates open circuit.
- Short-to-battery symptom: squib circuit measures approximately battery voltage (~11–13 V with ignition ON) at squib connector when it should be low/near zero with connector disconnected from SRS ECU
- Normal inactive squib line: no battery voltage present when connector is disconnected and ignition ON; only a small sensing voltage from ECU present (manufacturer-specific)
Diagnostic algorithm
- Safety: Disable SRS power — disconnect negative battery terminal and wait the specified time (refer to service manual) before probing or disconnecting airbag connectors.
- Scan & note: Read and record all SRS codes and freeze frame data with a capable scan tool. Do not clear codes yet.
- Visual inspection: Inspect steering column, clock spring area, driver airbag connector, harness along routing to ECU for damage, burnt areas, melted insulation, or corrosion.
- Isolate circuit: With battery reconnected (only when safe to measure), back-probe the squib circuit connector and check for battery voltage on the suspected pin with ignition ON. Presence of ~12 V indicates a short to battery.
- Measure resistance: With battery disconnected, measure resistance of driver squib circuit from connector to airbag module/connector. Compare to spec. Very low resistance may indicate short; very high indicates open.
- Narrow location: Disconnect connectors along harness (clock spring, intermediate connectors) and repeat voltage/resistance checks to localize the short to a module/connector/harness section.
- Inspect clock spring: If localized to steering column, remove and inspect/replace clock spring per service procedures; do not attempt internal repair unless qualified.
- Repair: Repair or replace damaged wiring, connectors, clock spring, or squib as required. Use OEM parts and proper crimping/soldering and insulation methods.
- Verify: Reconnect, clear codes with scan tool, perform SRS system readiness check and any required ECU initialization or calibration. Confirm code does not return and SRS lamp extinguishes.
- Final safety check: Restore battery and perform a final vehicle system check following manufacturer SRS procedures.
Likely causes
- Clock spring failure causing conductor to short to battery feed
- Pin-to-pin short or a pin pushed through terminal at steering column connector
- Wire chafed on sharp metal or contact with hot component and melted insulation contacting battery feed
- Corroded connector allowing conductive path to battery voltage after moisture ingress
Fault status
Status
Front airbag (driver) squib circuit shorted to battery — SRS control unit detected battery voltage on squib circuit; SRS warning lamp ON.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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