Code
B1490
MITSUBISHI
B — Body
F ABG(2)PS squib short
Views:
UK: 3
EN: 12
RU: 8
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring in the passenger squib circuit (short to ground or to battery)
- Corroded or loose connector at the passenger airbag/squib or SRS control unit
- Faulty passenger airbag module or squib (internal short)
- Poor repair after previous deployment (incorrect wiring or damaged components)
- Faulty SRS (airbag) control unit or internal driver failure
- Aftermarket accessories (seat heaters, alarms) incorrectly installed and interfering with squib circuit
Symptoms
- Illuminated SRS/airbag warning lamp on instrument cluster
- Passenger airbag indicator may show disabled or not operational
- SRS system self-check fails and may disable deployment of affected airbag
- Possible stored related SRS diagnostic trouble codes in control module
What to check
- Retrieve stored SRS codes and freeze-frame data with a compatible scanner
- Visual inspection of passenger seat area, connectors, and wiring harness for damage, corrosion, or water
- Check connector at passenger airbag and at SRS control unit for secure fit and bent pins
- Measure resistance of passenger squib circuit with ignition off and battery disconnected (compare to spec)
- Check for short to ground or short to battery on squib circuit using ohmmeter/short finder
- Inspect seat rails and connectors for pinching or chafing from seat movement
Signal parameters
- Battery voltage on SRS power lines: approx. 12–14 V with ignition ON (normal power rail)
- Passenger squib circuit static resistance (typical): low ohms range (commonly ~2–5 ohms for squib assemblies) — consult factory spec
- Open-circuit: very high resistance/OL if squib disconnected or open; short to ground: near 0 Ω
- Short-to-battery: squib circuit shows near 0 Ω to B+ when measuring to battery positive
- During normal operation the SRS unit fires a discharge pulse (do NOT attempt to trigger during diagnostics)
Diagnostic algorithm
- Safety first: Disable SRS power per manufacturer procedure — disconnect negative battery terminal and wait the specified time (typically several minutes) before touching SRS components. Consult the service manual.
- Read and record all SRS codes and freeze-frame data with an appropriate diagnostic tool. Note any other related codes.
- Visually inspect passenger seat, connector backshells, harness routing, and seat rail areas for damage, corrosion, water, or pinched wires.
- With battery still disconnected, disconnect the passenger airbag/squib connector. Measure resistance across the squib pins. Compare to factory spec. A very low resistance to chassis ground indicates a short to ground; a very low resistance to battery positive indicates a short to power.
- Perform continuity checks from the squib connector back to the SRS control unit pin to find wiring faults. Wiggle the seat and harness while monitoring continuity to reproduce intermittent shorts.
- Inspect and test connectors at the SRS control unit for corrosion, bent pins, or water intrusion. Repair or replace damaged connectors or terminals.
- If wiring and connectors check OK, consider replacing the passenger airbag assembly/squib (especially if resistance values are out of spec or there is evidence of internal shorting).
- If component replacement performed, clear codes, reconnect battery, and perform SRS system scan. Verify no recurrence of the B1490 code and that SRS lamp extinguishes after self-check.
- If code persists after repairing wiring and replacing components, suspect a faulty SRS control unit and verify its inputs/outputs per factory procedures before replacement.
Likely causes
- Shorted conductor in harness under or near passenger seat (pinched by seat rails)
- Connector pin corrosion or bent pin at the passenger airbag connector
- Seatbelt pretensioner/squib or passenger airbag assembly internal short
- Water ingress into connector or seat area causing shorts
- Damaged insulation from previous work (seat removal/installation)
Fault status
Status
Front passenger squib circuit short detected (short to battery or ground) — SRS control unit fault code B1490.
Repair difficulty: Hard
Diagnostic time: 1-3 hours
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