LEMON Manuals: Even more car manuals for everyone
Home >> Mitsubishi >> 2014 >> Lancer SE >> Repair and Diagnosis >> External Pages >> Different car >> Section 37 (Supplemental Restraint System (SRS) - With Diagnostics) >> SRS Air Bag Diagnosis >> Diagnostic Trouble Code Procedures >> DTC B1401: Driver's air bag module (1st squib) system (open circuit of squib circuit); DTC B1481: Driver's air bag module (2nd squib) system (open circuit of squib circuit) >> Diagnosis

DTC B1401: Driver's air bag module (1st squib) system (open circuit of squib circuit); DTC B1481: Driver's air bag module (2nd squib) system (open circuit of squib circuit): Diagnosis

WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.
  1. STEP 1. Using scan tool (M.U.T.-III), diagnose the CAN bus line. 
    CAUTION: To prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
    1. Connect scan tool (M.U.T.-III). 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? 

    1. YES:  Go to Step 2.
    2. NO:  Repair the CAN bus line (Refer to DIAGNOSIS ).
  2. STEP 2. Recheck for diagnostic trouble code. 

    Check again if the DTC is stored.

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

    Q: Is the DTC stored? 

    1. YES:  Go to Step 3.
    2. NO:  There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
  3. STEP 3. Check the diagnostic trouble code by connecting a dummy resistor. 
    1. Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
    2. Use the flat-tipped screwdriver to pull out the locking button of wiring harness side connector, and release the lock.
    3. Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866).
      CAUTION: Do not insert a probe directly into the terminal from the connector front side as the connector contact pressure may be weakened.
      Fig 1: Pulling Out Locking Button Of Wiring Harness Side Connector
      G09666491Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    4. Insert the resistor harness probe (special tool) as shown.
    5. Connect the negative battery terminal.
    6. After erasing the diagnostic trouble code memory, check the diagnostic trouble code again.
    7. Disconnect the negative battery terminal.
      CAUTION: Always DTC B1481 is stored when checking DTC B1401. This is because the second side terminal is isolated when checking it. DTC B1481 is stored but this is not a fault. In addition, always DTC B1401 is stored when checking DTC B1481 because the first side terminal is isolated.
      Fig 2: Identifying Air Bag Module Connector, Resistor And Harness
      G09666492Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    8. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

    Q: Is the checked DTC stored? 

    1. YES:  Go to Step 4.
    2. NO:  Replace the driver's air bag module (Refer to DRIVER'S AIR BAG MODULE AND CLOCK SPRING  ).
  4. STEP 4. Diagnosis check by dummy resistor connection. 
    1. Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
    2. Disconnect the clock spring connector.
    3. Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866).
      CAUTION: Do not insert a probe directly into the terminal from the connector front side as the connector contact pressure may be weakened.
    4. Insert the resistor harness probe from the back of harness side connector DQ1-, DQ1+ line < B1401 >.

      Insert the resistor harness probe from the back of harness side connector DQ2-, DQ2+ line < B1481 >.

    5. Connect the negative battery terminal.
    6. After erasing the diagnostic trouble code memory, check the diagnostic trouble code again.
    7. Disconnect the negative battery terminal.
      Fig 3: Identifying Clock Spring Connector, Resistor And Harness
      G09666493Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      CAUTION: Always DTC B1481 is stored when checking DTC B1401. This is because the second side terminal is isolated when checking it. DTC B1481 is stored but this is not a fault. In addition, always DTC B1401 is stored when checking DTC B1481 because the first side terminal is isolated.
    8. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

    Q: Is the checked DTC stored? 

    1. YES:  Go to Step 5.
    2. NO:  Replace the clock spring (Refer to DRIVER'S AIR BAG MODULE AND CLOCK SPRING  ).
  5. STEP 5. Resistance measurement at the SRS-ECU and the C-313 clock spring connectors 
    1. Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
    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 SRS-ECU connector.
      CAUTION: To release SRS-ECU connector short spring in the following operations, disconnect this clock spring connector, and keep the squib circuit shorted.
    3. Disconnect the clock spring connector.
      Fig 4: Disconnecting SRS-ECU Connector
      G09666494Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      CAUTION: The short spring may not be released due to the insufficient insertion. Therefore, insert the insulator for 4 mm (0.16 inch) or more.
    4. Insert the insulator [width: 3 mm (0.12 inch), thickness: 0.5 mm (0.02 inch)] such as cable tie between the DQ1-, DQ1+ line, and then release the short spring < B1401 >.

      Insert the insulator [width: 3 mm (0.12 inch), thickness: 0.5 mm (0.02 inch)] such as cable tie between the DQ2-, DQ2+ line, and then release the short spring < B1481 >.

      Fig 5: Identifying Harness Side Connector And Cable Tie (1st Squib)
      G09666495Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      Fig 6: Identifying Harness Side Connector And Cable Tie (2nd Squib)
      G09666496Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      CAUTION: Do not insert a probe directly into the terminal of clock spring connector harness side connector from the connector front side as the connector contact pressure may be weakened.
    5. Take the measurements below at the SRS-ECU connector and clock spring connector harness side connectors.
      • Continuity DQ1- line between SRS-ECU connector and clock spring connector < B1401 >
      • Continuity DQ1+ line between SRS-ECU connector and clock spring connector < B1401 >

        OK: Continuity (less than 2 Ω) 

      • Continuity DQ2- line between SRS-ECU connector and clock spring connector < B1481 >
      • Continuity DQ2+ line between SRS-ECU connector and clock spring connector < B1481 >

        OK: Continuity (less than 2 Ω) 

    Q: Is the check result normal? 

    1. YES:  Go to Step 6.
    2. NO:  Repair the wiring harnesses DQ1-, DQ1+ line < B1401 > or DQ1-, DQ1+ line < B1481 > between the clock spring connector and the SRS-ECU connector.
  6. STEP 6. Recheck for diagnostic trouble code. 

    Check again if the DTC is stored.

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

    Q: Is DTC B1401 < 1st squib > or B1481 < 2nd squib > stored? 

    1. YES:  Replace SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU)  ).
    2. NO:  Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
scientia non olet · About LEMON Manuals