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Home >> Mitsubishi >> 2019 >> Eclipse Cross ES, AWD >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Supplemental Restraint System (SRS) - (With Diagnostics) >> SRS Air Bag Diagnosis >> Diagnostic Trouble Code Procedures <SRS-Ecu> >> 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
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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

  1. STEP 1. Using scan tool (M.U.T.-IIISE), diagnose the CAN bus line. 
    CAUTION: To prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
    1. Connect scan tool (M.U.T.-IIISE). 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 ).

  2. 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 ).

  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 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.
      G11280620Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    4. Insert the resistor harness probe (special tool) as shown in the illustration.
    5. Connect the negative battery terminal.
    6. After erasing the DTC memory, check the DTC again.
    7. Disconnect the negative battery terminal.
      CAUTION: Always DTC B1481 is set when checking DTC B1401. This is because the second side terminal is isolated when checking it. DTC B1481 is set but this is not a fault. In addition, always DTC B1401 is set when checking DTC B1481 because the first side terminal is isolated.
    8. Erase the DTC memory, and check the diagnostic trouble code.

    Q: Is the checked DTC set? 

    YES  : Go to Step 4

    NO  : Replace the driver's air bag module (Refer to DRIVER'S AIR BAG MODULE AND CLOCK SPRING ).

    G11280622Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  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>.

      G11280623Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    5. Connect the negative battery terminal.
    6. After erasing the DTC memory, check the DTC again.
    7. Disconnect the negative battery terminal.
      CAUTION: Always DTC B1481 is set when checking DTC B1401. This is because the second side terminal is isolated when checking it. DTC B1481 is set but this is not a fault. In addition, always DTC B1401 is set when checking DTC B1481 because the first side terminal is isolated.
    8. Erase the DTC memory, and check the diagnostic trouble code.

    Q: Is the checked DTC set? 

    YES  : Go to Step 5

    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 clock spring connectors 
    1. Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
    2. 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.
      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>.

      G12148665Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      G12148666Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      CAUTION: Do not insert a probe directly into the terminal of clock spring 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 ohms) 

      • 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 ohms) 

    Q: Is the check result normal? 

    YES  : Go to Step 6

    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. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again. 

    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 B1401 <1st squib> or B1481 <2nd squib> set? 

    YES  : Replace SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU) ).

    NO  : Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).

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