DTC B1B0B: Passenger's (Front) Air Bag Module (1st Squib) System (Short Circuit Between Squib Circuit Terminals); DTC B1B0F: Passenger's (Front) Air Bag Module (2nd Squib) System (Short Circuit Between Squib Circuit Terminals): Diagnosis

Required Special Tools: 

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)
  • MB991824: Vehicle Communication Interface (V.C.I.)
  • MB991827: M.U.T.-III USB Cable
  • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN Communication System)
• MB991865: Dummy resister
• MB991866: Resister harness

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  ."
   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 .
        Fig 1: Connecting Scan Tool To Data Link Connector

        Courtesy 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 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 .
        Fig 2: Connecting Scan Tool To Data Link Connector

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. STEP 3. Check SRS-ECU connector C-28 and passenger's (front) air bag module connector C-11. (Using scan tool MB991958, read the diagnostic trouble code.) 
   1. Disconnect the negative battery terminal.
   2. Disconnect connectors C-28 and C-11, and then reconnect them.
      • While pushing the part "A" indicated in the illustration of the harness side connector, turn the lock lever to the direction of the arrow to release the lock lever, and disconnect the C-28 SRS-ECU connector.
        Fig 3: Releasing Lock Lever

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      • Slide the outer housing of passenger's (front) air bag module connector C-11 in the arrow direction shown in the illustration, and disconnect the connector.
   3. Connect the negative battery terminal.
   4. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

      Q: Is DTC B1B0B < 1st squib > or B1B0F < 2nd squib > set? 

      • YES:  Go to Step 4.
      • NO:  The procedure is complete. It is assumed that DTC B1B0B < 1st squib > or B1B0F < 2nd squib > set as connector C-28 or C-11 was engaged improperly.
        Fig 4: Sliding Outer Housing Of Passenger's Front Air Bag Module Connector C-11

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
4. STEP 4. Check the passenger's (front) air bag module. (Using scan tool MB991958, read the diagnostic trouble code.) 
   1. Disconnect the negative battery terminal.
   2. Slide the outer housing of passenger's (front) air bag module connector C-11 in the arrow direction shown in the illustration, and disconnect the connector.
      Fig 5: Sliding Outer Housing Of Passenger's Front Air Bag Module Connector C-11

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   3. Connect special tool MB991865 to special tool MB991866.
      CAUTION: Do not insert a probe into the terminal from its front side directly as the connector contact pressure may be weakened.
      Fig 6: Inserting Special Tool MB991866 Into Harness Side Connector C-11 Terminals

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   4. Insert special tool MB991866 into the harness side connector C-11 (terminal No. 1 and 2 < 1st squib > or terminal No. 3 and 4 < 2nd squib >) by backprobing.
   5. Connect the negative battery terminal.
      CAUTION: Always DTC B1B0E is set when checking DTC B1B0B. This is because the second side terminal is isolated when checking it. DTC B1B0E is set but this is not a fault. In addition, always DTC B1B0A is set when checking DTC B1B0F because the first side terminal is isolated.
   6. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

      Q: Is the checked DTC set? 

      • YES:  Go to Step 5.
      • NO:  Replace the passenger's air bag module (Refer to AIR BAG MODULE(S) AND CLOCK SPRING  . Then go to Step  7.
5. STEP 5. Check the passenger's (front) air bag module circuit at SRS-ECU connector C-28. 
   1. Disconnect the negative battery terminal.
   2. While pushing the part "A" indicated in the illustration of the harness side connector, turn the lock lever to the direction of the arrow to release the lock lever, and disconnect the C-28 SRS-ECU connector.
      Fig 7: Releasing Lock Lever

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      WARNING: To prevent the air bag from deploying unintentionally, disconnect the passenger's (front) air bag module connector C-11 to short the squib circuit.
   3. Slide the outer housing of passenger's (front) air bag module connector C-11 in the arrow direction shown in the illustration, and disconnect the connector.
      Fig 8: Sliding Outer Housing Of Passenger's Front Air Bag Module Connector C-11

      Courtesy 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.
   4. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 7 and 8 < 1st squib > or 11 and 12 < 2nd squib >, and the short spring to release the short spring.
      Fig 9: Inserting Cable Tie Between Terminals 7 And 8 (1st Squib) And Short Spring

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      Fig 10: Inserting Cable Tie Between Terminals 11 And 12 (2nd Squib) And Short Spring

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   5. Check for continuity between C-28 harness side connector terminals 7 and 8 < 1st squib > or 11 and 12 < 2nd squib >.

      It should be open circuit.

      Q: Is it open circuit? 

      • YES:  Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1B0B < 1st squib > or B1B0F < 2nd squib > set, replace the SRS-ECU. (Refer to SRS CONTROL UNIT (SRS-ECU)  . and then go to Step  7.
      • NO:  Go to Step 6.
        Fig 11: Checking Continuity Between C-28 Harness Side Connector Terminals 7 And 8

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
        Fig 12: Checking Continuity Between C-28 Harness Side Connector Terminals 11 And 12

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
6. STEP 6. Check the harness for short circuit between the harness wire and wire. 
   • SRS-ECU connector C-28 (terminal No. 7 and 8) and passenger's (front) air bag module connector C-11 (terminal No. 2 and 1) < 1st squib >.
   • SRS-ECU connector C-28 (terminal No. 11 and 12) and passenger's (front) air bag module connector C-11 (terminal No. 4 and 3) < 2nd squib >.

     Q: Is the check result normal? 

     • YES:  Go to Step 7.
     • NO:  Repair the harness wires between SRS-ECU connector C-28 and passenger's (front) air bag module connector C-11. Then go to Step 7.
7. STEP 7. Check 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 B1B0B < 1st squib > or B1B0F < 2nd squib > set? 

      • YES:  Return to Step  1.
      • NO:  The procedure is complete.
        Fig 13: Connecting Scan Tool To Data Link Connector

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.