DTC B1C3A: Driver's Pre-TENSIONER (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
MB991884: 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 the "ON" position.
3. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?

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 the "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 driver's seat belt pre-tensioner.
1. Disconnect the negative battery terminal.
2. Disconnect driver's seat belt pre-tensioner connector D-25. Use a flat-tipped screwdriver to unlock the locking button at the harness side connector by withdrawing it toward you in two stages, and then disconnect the connector.
  
  Fig 2: Disconnecting Driver's Seat Belt Pre-Tensioner Connector D-25
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. Connect special tool MB991865 to special tool MB991884.
4. Connect special tool MB991884 to the D-25 harness side connector.
5. Connect the negative battery terminal.
6. Erase diagnostic trouble code memory, and then check the diagnostic trouble code.
Q: Is DTC B1C3A set?

YES : Go to Step 4.

NO : Replace the driver's seat belt with pre-tensioner (Refer to SEAT BELTS WITH PRE-TENSIONER ). Then go to Step 5.

Fig 3: Connecting Special Tool MB991884 To D-25 Harness Side Connector
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 4. Check the harness for open circuit between SRS-ECU connector C-36 (terminal No. 45 and 46) and the driver's seat belt pre-tensioner D-25 (terminal No. 1 and 2).
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 4: Turning Lock Lever
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  
  DANGER
  
  To prevent the seat belt pre-tensioner from deploying unintentionally, disconnect the driver's seat belt pre-tensioner connector D-25 to short the squib circuit.
3. Disconnect SRS-ECU connector C-36 and driver's seat belt pre-tensioner connector D-25, and measure at the wiring harness side. For connector D-25, use a flat-tipped screwdriver to unlock the locking button at the harness side connector by withdrawing it toward you in two stages, and then disconnect the connector.
  
  Fig 5: Disconnecting Driver's Seat Belt Pre-Tensioner Connector D-25
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  
  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 45, 46 and the short spring to release the short spring.
  
  Fig 6: Inserting Cable Tie Between Terminals 45, 46 And Short Spring
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
5. Connect D-25 harness side connector to special tool MB991884.
  
  Fig 7: Connecting D-25 Harness Side Connector To Special Tool MB991884
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
6. Check for continuity between the following terminals. It should be less than 2 ohms.
  - SRS-ECU connector C-36 (terminal No. 45) and the special tool (terminal No. 2)
  - SRS-ECU connector C-36 (terminal No. 46) and the special tool (terminal No. 1)
Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and recheck if any DTC set. If DTC B1C3A set, replace the SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU) ). Then go to Step 5.

NO : Replace harness wires between SRS-ECU connector C-36 and driver's seat belt pre-tensioner connector D-25. Then go to Step 5.

Fig 8: Checking Continuity Between SRS-ECU Connector C-36 (Terminal No. 45) And Special Tool (Terminal No. 2)
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
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 B1C3A set?

YES : Return to Step 1.

NO : The procedure is complete.