LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mitsubishi >> 2006 >> Eclipse GT, Automatic >> Repair and Diagnosis >> Restraints >> Restraints Control Systems >> Supplemental Restraint System >> SRS Air Bag Diagnosis >> Diagnostic Trouble Code Procedures >> DTC B1420: Side-Airbag Module (RH) (Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit) >> Diagnosis
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC B1420: Side-Airbag Module (RH) (Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit): Diagnosis

Required Special Tools: 

  1. 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 (MUT-III)  ."
    2. Turn the ignition switch to "ON" position.
    3. Diagnose the CAN bus line.
    4. Turn the ignition switch to the "LOCK" (OFF) position.

    Q: Is the check result satisfactory? 

    YES :  Go to Step 2

    NO :  Repair the CAN bus lines (Refer to DIAGNOSIS ).

    Fig 1: Connecting Scan Tool To Data Link Connector
    G04230562Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  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 "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 Use Troubleshooting/Inspection Service Points - HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).

    Fig 2: Connecting Scan Tool To Data Link Connector
    G04230562Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  3. STEP 3. Using scan tool MB991958, read the diagnostic trouble code. 
    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. Turn the ignition switch to the "ON" position.
    2. Check if the DTC is set.
    3. Turn the ignition switch to the "LOCK" (OFF) position.

    Q: Is DTC B1519 set? 

    YES :  Go to Step 4.

    NO :  Go to  Step 5.

    Fig 3: Connecting Scan Tool To Data Link Connector
    G04230562Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  4. STEP 4. Check SRS-ECU connector C-124. 

    Q: Is the connector correctly engaged? 

    YES :  Go to Step 5.

    NO :  Engage the connector correctly. Then go to  Step 9.

    Fig 4: Identifying Connector C-124 Terminals
    G04238013Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  5. STEP 5. Check SRS-ECU connector C-124 and side-airbag module (RH) connector D-28. (Using scan tool MB991958, read the diagnostic trouble code.) 
    1. Disconnect the negative battery terminal.
    2. Disconnect connectors C-124 and D-28, and then reconnect them.
    3. Connect the negative battery terminal.
    4. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

    Q: Is DTC B1420 out put? 

    YES :  Go to Step 6.

    NO :  The procedure is complete. It is assumed that DTC B1420 set because connector C-124 or D-28 was engaged improperly.

    Fig 5: Identifying Connector C-124 Terminals
    G04238013Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    Fig 6: Identifying Connector D-28 Terminals
    G04238014Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  6. STEP 6. Check the side-airbag module (RH). (Using scan tool MB991958, read the diagnostic trouble code.) 
    1. Disconnect the negative battery terminal.
    2. Disconnect the side-airbag module (RH) connector D-28.
      Fig 7: Identifying Connector D-28 Terminals
      G04238014Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    3. Connect special tool MB991865 to special tool MB991866.
      CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.
    4. Insert special tool MB991866 into the D-28 harness side connector by backprobing.
    5. Connect the negative battery terminal.
    6. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

    Q: Is DTC B1420 set? 

    YES :  Go to Step 7.

    NO :  Replace the seatback frame of the front seat (RH) (Refer to < DRIVER'S SEAT > ). Then go to  Step 9.

    Fig 8: Inserting Special Tool MB991866 Into D-28 Harness Side Connector
    G04238016Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  7. STEP 7. Check the side-airbag module (RH) circuit. Measure the resistance at the SRS-ECU connector C-124. 
    1. Disconnect SRS-ECU connector C-124.
      Fig 9: Identifying Connector C-124 Terminals
      G04238013Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      WARNING: To prevent the air bag from deploying unintentionally, disconnect the side-airbag module (RH) connector D-28 to short the squib circuit.
    2. Disconnect side-airbag module connector D-28.
      Fig 10: Identifying Connector D-28 Terminals
      G04238014Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      CAUTION: Insert an insulator such as a cable tie to a depth of 4 mm (0.16 inch) or more, otherwise the short spring will not be released.
    3. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 57, 58 and the short spring to release the short spring.
    4. Measure at the wiring harness side.
      Fig 11: Inserting Cable Tie Between Terminals 27, 28 And Short Spring (1st Squib)
      G04238019Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.
    5. Check for continuity between C-124 harness side connector terminals 57 and 58.

    It should be open circuit.

    Q: Does continuity exist? 

    YES :  Go to Step 8.

    NO :  Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1420 sets, replace the SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU)  ). Then go to Step 7.

    Fig 12: Checking Continuity Between C-124 Harness Side Connector Terminals 57 And 58
    G04238020Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  8. STEP 8. Check the harness wires for short circuit between SRS-ECU connector C-124 (terminal No. 57 and 58) and side-airbag module (RH) connector D-28 (terminal No. 1 and 2). 

    Q: Are the harness wires between SRS-ECU connector C-124 (terminal No. 57 and 58) and side-airbag module (RH) connector D-28 (terminal No. 1 and 2) in good condition? 

    YES :  Go to Step 9.

    NO :  Repair the harness wires between SRS-ECU connector C-124 and side-airbag module (RH) connector D-28. Then go to Step 9.

    Fig 13: Identifying Connector C-124 Terminals
    G04238013Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
    Fig 14: Identifying Connector D-28 Terminals
    G04238014Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  9. STEP 9. 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 B1420 set? 

    YES :  Return to  Step 1.

    NO :  The procedure is complete.

    Fig 15: Connecting Scan Tool To Data Link Connector
    G04230562Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
scientia non olet · About LEMON Manuals