B1401 – Driver’s air bag module (squib) system (open- circuited in the squib circuit) MMC Colt

---

---

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 input to the air bag module via the clock spring to inflate the air bag.

---

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal resistance between the input terminals of the driver’s side air bag module (squib). The most likely causes for this code to be set are the followings:

Open circuit in the driver’s air bag module (squib) or harness

Open circuit in the clock spring

Malfunction of connector contact

---

PROBABLE CAUSES

Open circuit in the clock spring

Open circuit due to improper neutral position of the clock spring

Open circuit in the driver’s air bag module (squib) circuit

Disengaged driver’s air bag module (squib) connector

Improper connector contact

Malfunction of the SRS-ECU

---

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 B1401 set?

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

Q. Is diagnosis code B1401 set?

STEP 5. Resistance measurement between the SRS-ECU connector B-109 (terminal No.24 and 25) and the clock spring connector B-243 (terminal No.13 and 14).

SRS-ECU connector B-109 (terminal No.24) and the clock spring connector B-243 (terminal No.13)

SRS-ECU connector B-109 (terminal No.25) and the clock spring connector B-243 (terminal No.14)

Q. Are the check results normal?

STEP 6. Check whether the diagnosis code is reset.

Q. Is diagnosis code B1401 set?