DTC B1420: Side-airbag module (RH) (squib) system (short circuit between squib circuit terminals): 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.

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 "ON" position.
3. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
1. YES: Go to Step 2.
2. NO: Repair the CAN bus line (Refer to DIAGNOSIS ).
STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is stored.
1. Erase the DTC.
2. Turn the ignition switch to "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: Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
STEP 3. Connector check: SRS-ECU, side-airbag module (RH).
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.
  
  Fig 1: Disconnecting SRS-ECU Connector
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. After disconnecting the side-airbag module (RH) connector, connect the connector again. For the side-airbag module (RH) connector disconnection, unlock the connector by sliding the locking button to the direction of the arrow as shown in the figure, and then disconnect the connector.
4. Connect the negative battery terminal.
5. After erasing the diagnostic trouble code memory, check the DTC again.
6. Disconnect the negative battery terminal.
Q: Is DTC B1420 stored?
1. YES: Go to Step 4.
2. NO: Replace the connector concerned.
  
  Fig 2: Disconnecting Side-Airbag Module Connector
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
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 side-airbag module (RH) connector, unlock the connector by sliding the locking button to the direction of the arrow as shown in the figure, and then disconnect the connector.
  
  Fig 3: Disconnecting Side-Airbag Module Connector
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
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 side-airbag module (RH) harness side connector.
5. Connect the negative battery terminal.
6. After erasing the diagnosis trouble code memory, check the diagnostic trouble code again.
7. Disconnect the negative battery terminal.
  
  Fig 4: Identifying Side Airbag Module Connector And Special Tools
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Q: Is DTC B1420 stored?
1. YES: Go to Step 5.
2. NO: Replace the front seatback pad and frame assembly (Refer to SIDE-AIRBAG MODULE(S) ).
STEP 5. 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.
  WARNING: To release the connector short spring in the following operations, disconnect this side-airbag module connector, and keep the squib circuit shorted.
  
  Fig 5: Disconnecting SRS-ECU Connector
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. Disconnect the side-airbag module (RH) connector, unlock the connector by sliding the locking button to the direction of the arrow as shown in the figure, and then disconnect the connector.
  
  Fig 6: Disconnecting Side-Airbag Module Connector
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  
  CAUTION: The short spring may not be released due to the insufficient insertion, thus insert for 4 mm (0.16 inch) or more.
4. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between the SRS+, SRS- line and the short spring, and then release the short spring.
5. Take the measurements below at the side-airbag module (RH) harness side connector.
  - Continuity between SRS+, SRS- line
    OK: No continuity
Q: Is the check result normal?
1. YES: Go to Step 6.
2. NO: Repair the wiring harness SRS+, SRS- line between the side-airbag module (RH) connector and the SRS-ECU connector.
  
  Fig 7: Identifying Harness Side Connector And Cable Tie
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
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 B1420 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 ).