DTC B1C29: Side-Air Bag Module (LH) (Squib) System (Squib Circuit Open): Diagnosis

WARNING: This page is about a different car, the 2008 Mitsubishi Lancer. However, it is still accessible from the selected car via links, so may be relevant.

Required Special Tools:

MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V. C. I).
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
MB991865: Dummy resistor
MB991866: Resister harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958. Refer to "HOW TO CONNECT THE SCAN TOOL ".
2. Turn the ignition switch to "ON" position.
3. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : Go to Step 2.

NO : Repair the CAN bus line (Refer to DIAGNOSIS ).

Fig 1: Connecting Special Tool MB991910 To Data Link Connector
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
1. Erase the DTC.
2. Turn the ignition switch to "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?

YES : Go to Step 3.

NO : There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
STEP 3. Check the side-air bag module (LH).
1. Disconnect the negative battery terminal.
2. Disconnect the side-air bag module (LH) connector D-34.
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-34 harness side connector by backprobing.
5. Connect the negative battery terminal.
6. Erase diagnostic trouble code memory, and then check the diagnostic trouble code.
  
  Fig 2: Inserting Special Tool MB991866 Into D-34 Harness Side Connector
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Q: Is DTC B1C29 set?

YES : Go to Step 4.

NO : Replace the front seatback (Refer to FRONT SEAT ASSEMBLY ). Then go to Step 5.
STEP 4. Check the harness for open circuit between the SRS-ECU connector C-36 (terminal No. 31 and 32) and the side-air bag module (LH) connector D-34 (terminal No. 2 and 1).
1. Disconnect the negative battery terminal.
2. While pushing the part "A" indicated in the figure of the harness side connector, turn the lock lever to the direction of the arrow to release the lock lever, and disconnect the C-36 SRS-ECU connector.
  
  Fig 3: Turning Lock Lever
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  
  DANGER
  
  To prevent the air bag from deploying unintentionally, disconnect the side-air bag module (LH) connector D-34 to short the squib circuit.
3. Disconnect side-air bag module (LH) connector D-34.
  CAUTION: Insert an insulator such as a cable tie to a depth of 4mm (0.16 inch) or more, otherwise the short spring will not be released.
4. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 31, 32 and the short spring to release the short spring.
  
  Fig 4: Inserting Cable Tie Between Terminals 31, 32 And Short Spring
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  
  CAUTION: Do not insert a test probe into the terminal from D-34 harness side connector front side directly, as the connector contact pressure may be weakened.
5. Check for continuity between the following terminals. It should be less than 2 ohms.
  - SRS-ECU connector C-36 (terminal No. 31) and the side-air bag module (LH) connector D-34 (terminal No. 2)
  - SRS-ECU connector C-36 (terminal No. 32) and the side-air bag module (LH) connector D-34 (terminal No. 1)
    
    Fig 5: Checking Continuity Between SRS-ECU Connector C-36 And Side-Air Bag Module (LH) Connector D-34
    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1C29 sets, replace the SRS-ECU. Refer to SRS CONTROL UNIT (SRS-ECU) . Then go to Step 5.

NO : Replace the harness wires between SRS-ECU connector C-36 and side-air bag module (LH) connector D-34. Then go to Step 5.
STEP 5. 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 B1C29 set?

YES : Return to Step 1.

NO : The procedure is complete.