B1431

This document has been updated per Mitsubishi TSB# 06-52b-001



DTC B1431: Side-Airbag Module (LH) (Squib) System Fault 2 (Open in the Squib Circuit)

Side-Airbag Module (LH) (Squib) Circuit:

CIRCUIT OPERATION
- The SRS-ECU judges how severe a collision is by detecting signals from the left and right side impact sensors. If the impact is over a predetermined level, the SRS-ECU outputs an ignition signal. At this time, if the side-airbag safing G-sensor is on, the SRS side-airbag will inflate.
- The ignition signal is input to the side-airbag module to inflate the side-airbag.

DTC SET CONDITIONS
This DTC is set if there is abnormal resistance between the input terminals of the side-airbag module (LH) (squib).

TROUBLESHOOTING HINTS
- Open circuit in the side-airbag module (squib) (LH) circuit
- Improper connector contact
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: MUT-III USB Cable
- MB991910: MUT-III Main Harness A
- MB991865: Dummy resister
- MB991866: Resister harness

STEP 1. Check the side-airbag module (LH) (Using scan tool MB991958, read the diagnostic trouble code).




1. Disconnect the negative battery terminal.
2. Disconnect the side-airbag module (LH) connector D-19.




3. Connect special tool MB991865 to special tool MB991866.

CAUTION: Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.

4. Insert special tool MB991866 into the D-19 harness connector by backprobing.
5. Connect the negative battery terminal.
6. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

Q: Is DTC B1431 set?

YES: Go to Step 2.

NO: Replace the seat back assembly of the front seat (LH) (Refer to Interior, Front Seat). Then go to Step 3.

STEP 2. Check the harness for open circuit between the SRS-ECU connector C-29 (terminal No.9 and 10) and the side-airbag module (LH) D-19 (terminal No.1 and 2).




1. Disconnect SRS-ECU connector C-29.




2. Disconnect side-airbag module (LH) connector D-19.

CAUTION: Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.




3. Check for continuity between the following terminals.
- SRS-ECU connector C-29 (terminal No.9) and the side-airbag module (LH) connector D-19 (terminal No.1)
- SRS-ECU connector C-29 (terminal No.10) and the side-airbag module (LH) connector D-19 (terminal No.2)

It should be less than 2 ohms.

Q: Does continuity exist?

YES: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1431 sets, replace the SRS-ECU. Then go to Step 3.

NO: Repair the harness wires between SRS-ECU connector C-29 and side-airbag module (LH) connector D-19. Then go to Step 3.

STEP 3. Recheck for diagnostic trouble code.




Check again if the DTC is set.
1. Erase the DTC.
2. Turn the ignition switch to the "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC B1431 set?

YES: Return to Step 1.

NO: The procedure is complete.