DTC 25: Passenger's (Front) Air Bag Module (Squib) System Fault 2 (Open in the Squib Circuit): Diagnosis

Required Special Tools: 

• MB991958: Scan Tool (MUT-III Sub Assembly)
  • MB991824: Vehicle Communication Interface (V.C.I.)
  • MB991827: MUT-III USB Cable
  • MB991911: MUT-III Main Harness B (Vehicles without CAN communication system)
• MB991865: Dummy resister
• MB991866: Resister harness

1. STEP 1. Check the passenger's air bag module (Using scan tool MB991958, read the diagnostic trouble code). 
   1. Disconnect the negative battery terminal.
   2. Unclip passenger's air bag module connector C-106.
      Fig 1: Identifying Air Bag Module Harness Connector C-106

      Courtesy 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. Disconnect the passenger's air bag module connector C-106, and insert special tool MB991866 into the harness 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 25 set? 

   • YES:  Go to Step 2.
   • NO:  Replace the passenger's air bag module (Refer to AIR BAG MODULES AND CLOCK SPRING  .) Then go to  Step 3.
     Fig 2: Checking Continuity Between C-106 Harness Connector

     Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
2. STEP 2. Check the harness for open circuit between SRS-ECU connector C-12 (terminal No.9 and 10) and the passenger's air bag module connector C-106 (terminal No.1 and 2.) 
   1. Unclip passenger's air bag module connector C-106.
      Fig 3: Identifying Harness Air Bag Module Connector C-106

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   2. Disconnect SRS-ECU connector C-12 and passenger's air bag module connector C-106.
      Fig 4: Identifying Harness SRS-ECU Connector C-12

      Courtesy 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.
   3. Check for continuity between the following terminals.
      • SRS-ECU connector C-12 (terminal No.9) and the passenger's air bag module connector C-106 (terminal No.2)
      • SRS-ECU connector C-12 (terminal No.10) and the passenger's air bag module connector C-106 (terminal No.1)

      It should be less than 2 ohms.

      Q: Does continuity exist? 

      • YES:  Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC 25 sets, replace the SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU)  .) Then go to Step 3.
      • NO:  Repair the harness wires between SRS-ECU connector C-12 and passenger's air bag module connector C-106. Then go to Step 3.
        Fig 5: Checking Continuity Between C-12 Harness Connector Terminals 9 And 10

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   4. STEP 3. Recheck for diagnostic trouble code. 

      Q: Is DTC 25 set? 

      • YES:  Return to  Step 1.
      • NO:  The procedure is complete (If no malfunctions are found in all steps, an intermittent malfunction is suspected. Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .)