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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 B1451: Curtain air bag module (LH) (squib) system (open circuit of squib circuit) >> Diagnosis

DTC B1451: Curtain air bag module (LH) (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. 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. Use the flat-tipped screwdriver to pull out the locking button of curtain air bag module connector to the direction of the arrow. After releasing the lock, disconnect the connector.
      Fig 1: Pulling Out Locking Button
      G09666610Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    3. Connect the dummy resistor (Special tool: MB991865) to the resistor harness (Special tool: MB991884).
    4. Connect the resistor harness (special tool) to curtain air bag module (LH) connector.
    5. Connect the negative battery terminal.
    6. After erasing the DTC memory, check the DTC again.
    7. Disconnect the negative battery terminal.

    Q: Is the DTC B1451 stored? 

    1. YES:  Go to Step 4.
    2. NO:  Replace the curtain air bag module (LH) (Refer to CURTAIN AIR BAG MODULE(S)  ).
      Fig 2: Identifying Curtain Air Bag Module Connector And Special Tools
      G09666611Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  4. STEP 4. Resistance measurement at the SRS-ECU connector and the curtain air bag module (LH) connector. 
    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.
      WARNING: To release SRS-ECU wiring harness side connector short spring in the following operations, disconnect curtain air bag module connector in advance, and keep the squib circuit shorted.
      Fig 3: Disconnecting SRS-ECU Connector
      G09666612Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    3. Use the flat-tipped screwdriver to pull out the locking button of curtain air bag module (LH) connector to the direction of the arrow. After releasing the lock, disconnect the connector.
      Fig 4: Pulling Out Locking Button
      G09666613Courtesy 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 an insulator [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] such as cable tie between the CLS+, CLS- line and the short spring, and release the short spring.
      Fig 5: Identifying Harness Side Connector And Cable Tie
      G09666614Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    5. Connect the resistor harness (Special tool: MB991884) to the removed curtain air bag module (LH) connector.
      NOTE: When the resistor harness is connected, the terminal No. of connected side and the CLS+, CLS- line of resistor harness connector will become inverted.
      Fig 6: Identifying Curtain Air Bag Module Connector And Special Tool
      G09666615Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    6. Take the following measurements.
      • Continuity CLS+ line between SRS-ECU wiring harness side connector and the resistor harness connector
      • Continuity CLS- line between SRS-ECU wiring harness side connector and the resistor harness connector

        OK: Continuity (less than 2 Ω) 

    Q: Is the check result normal? 

    1. YES:  Go to Step 5.
    2. NO:  Repair the wiring harness.
      Fig 7: Checking Continuity CLS+ Line Between SRS-ECU Wiring Harness Side Connector And Resistor Harness Connector
      G09666616Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  5. STEP 5. 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 B1451 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 ).
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