B1402 – Driver’s air bag module (squib) system (short-circuited to the earth) MMC Colt

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OPERATION

The SRS-ECU judges how severe a collision is by detecting signals from the front air bag analogue G-sensor. If the impact is over a predetermined level, the SRS-ECU sends an ignition signal. At this time, if the front air bag safing G-sensor is on, the SRS air bag will inflate.

The ignition signal is sent to the air bag module via the clock spring to inflate the air bag.

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DIAGNOSIS CODE SET CONDITIONS

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PROBABLE CAUSES

Malfunction of the clock spring

Damaged harness wires and connectors

Short to the earth in the driver’s air bag module (squib) harness

Malfunction of the SRS-ECU

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DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics.

Q. Is the CAN bus line found to be normal?

STEP 2. Check whether the diagnosis code is reset.

Q. Is the diagnosis code set?

STEP 3. Check the driver’s air bag module (M.U.T.-III diagnosis code).

Q. Is diagnosis code B1402 set?

STEP 4. Check the clock spring (M.U.T.-III diagnosis code).

Q. Is diagnosis code B1402 set?

STEP 5. Resistance measurement at the SRS-ECU connector B-109.

Q. Are the check results normal?

STEP 6. Check whether the diagnosis code is reset.

Q. Is diagnosis code B1402 set?