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Home >> Mitsubishi >> 2017 >> Mirage ES, Standard Trans >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Supplemental Restraint System (SRS) >> SRS Air Bag Diagnosis >> Diagnostic Trouble Code Procedures <SRS-Ecu> >> DTC B1400: Driver's Air Bag Module (1st Squib) System (Short Circuit Between Squib Circuit Terminals); Dtc B1480: Driver's Air Bag Module (2nd Squib) System (Short Circuit Between Squib Circuit Terminals) >> Diagnosis
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DTC B1400: Driver's Air Bag Module (1st Squib) System (Short Circuit Between Squib Circuit Terminals); Dtc B1480: Driver's Air Bag Module (2nd Squib) System (Short Circuit Between Squib Circuit Terminals): Diagnosis

  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? 

    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 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? 

    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. Connector check: SRS-ECU, clock spring, driver's air bag module. 
    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. After disconnecting the SRS-ECU connector, connect it again.
    3. After disconnecting clock spring, connect it again.
      Fig 1: Disconnecting SRS-ECU Connector Lock Lever
      G11280619Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    4. Disconnect the driver's air bag module connector using the Flat-tipped screwdriver to pull out the locking button to the direction of the arrow, and connect it again.
    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.

    Q: Is DTC B1400 <1st squib> or B1480 <2nd squib> stored? 

    YES:  Go to Step  4.

    NO:  Replace the connector concerned.

    Fig 2: Removing Driver Airbag Module Harness Side Connector Locking Button
    G11280620Courtesy 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. 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).
      Fig 3: Removing Driver Airbag Module Harness Side Connector Locking Button
      G11280620Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      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 (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 B1480 is stored when checking DTC B1400. This is because the second side terminal is isolated when checking it. DTC B1480 is stored but this is not a fault. In addition, always DTC B1400 is stored when checking DTC B1480 because the first side terminal is isolated.
    8. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

    Q: Is DTC B1400 <1st squib> or B1480 <2nd squib> stored? 

    YES:  Go to Step  5.

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

    Fig 4: Airbag Module Connector, Resistor Harness And Dummy Resistor
    G11280622Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  5. STEP 5. 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 <B1400>.

      Insert the resistor harness probe from the back of harness side connector DQ2-, DQ2+ line <B1480>.

    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 B1480 is stored when checking DTC B1400. This is because the second side terminal is isolated when checking it. DTC B1480 is stored but this is not a fault. In addition, always DTC B1400 is stored when checking DTC B1480 because the first side terminal is isolated.
      Fig 5: Clock Spring Connector, Dummy Resistor And Resistor Harness
      G11280623Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    8. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

    Q: Is DTC B1400 <1st squib> or B1480 <2nd squib> stored? 

    YES:  Go to Step  6.

    NO:  Replace the clock spring (Refer to DRIVER'S AIR BAG MODULE AND CLOCK SPRING ).

  6. STEP 6. Resistance measurement at the SRS-ECU 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.
      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 an insulator for 4 mm (0.16 inch) or more.
      Fig 6: Disconnecting SRS-ECU Connector Lock Lever
      G07049486Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    4. Insert an 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 <B1400>.

      Insert an 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 <B1480>.

    5. Take the measurements below at the harness side connector.
    • Continuity between DQ1-, DQ1+ line <B1400>

    OK: No continuity 

    • Continuity between DQ2-, DQ2+ line <B1480>

    OK: No continuity 

    Q: Is the check result normal? 

    YES:  Go to Step  7.

    NO:  Repair the wiring harnesses DQ1-, DQ1+ line <B1400> or DQ2-, DQ2+ line <B1480> between the clock spring connector and the SRS-ECU connector.

  7. STEP 7. Recheck for diagnostic trouble code. 

    Check again if the DTC is stored.

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

    Q: Is DTC B1400 <1st squib> or B1480 <2nd squib> stored? 

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

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

    Fig 7: Checking Short Spring Dimensions
    G11280625Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
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