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
- MB991827: MUT-III USB Cable
- MB991911: MUT-III Main Harness B
MB991865: Dummy resister
MB991866 Resister harness

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-11.
  
  Fig 1: Identifying Passenger's Air Bag Module Connector C-11
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  
  Fig 2: Disconnecting Passenger's 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 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-11, and insert special tool MB991866 into the harness side connector by backprobing.
5. Connect the negative battery terminal.
6. Erase the DTC memory, and then recheck the DTC.
Q: Is DTC 25 set?
1. YES: Go to Step 2.
2. NO: Replace the passenger's air bag module. Refer to INSPECTION . Then go to Step 3.
STEP 2. Check the harness for open circuit between SRS-ECU and the passenger's side air bag module.
1. Unclip passenger's air bag module connector C-11.
  
  Fig 3: Identifying SRS-ECU Connector C-72
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
2. Disconnect SRS-ECU connector C-72 and passenger's air bag module connector C-11, and measure at the wiring harness side.
  CAUTION: Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.
  
  Fig 4: Identifying Passenger's Air Bag Module C-11 Connector Terminal
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. Check for continuity between the following terminals.
  - SRS-ECU connector C-72 (terminal No. 5) and the passenger's air bag module connector C-11 (terminal No. 2)
  - SRS-ECU connector C-72 (terminal No. 6) and the passenger's air bag module connector C-11 (terminal No. 1)
  - Should be less than 2 ohms.
  Fig 5: Measuring Resistance Between SRS-ECU Connector C-72 And Passenger's Side Air Bag Module Connector C-11
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Q: Does continuity exist?
1. YES: Erase the DTC memory, and recheck if any DTC. If DTC 25 sets, replace the SRS-ECU. Refer to HARNESS CONNECTOR . Then go to Step 3.
2. NO: Repair the harness wires between SRS-ECU connector C-72 and passenger's side air bag module connector C-11. Then go to Step 3.
STEP 3. Recheck for diagnostic trouble code.
Q: Is DTC 25 set?
1. YES: Return to Step 1.
2. 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 MALFUNCTIONS ).