DTC 86:Left Hand Side-Airbag Module (Squib) System Fault Ground Circuit (Short-Circuit to Ground): 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

1. STEP 1. Check the side-airbag module (LH) (Using scan tool MB991958, read the diagnostic trouble code). 
   1. Disconnect the negative battery terminal.
   2. 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.
      Fig 1: Connecting Special Tool MB991865 To Special Tool MB991866

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   3. Disconnect the left hand side-airbag module (LH) connector D-15, and insert special tool MB991866 into the harness side connector by backprobing.
   4. Connect the negative battery terminal.
   5. Erase the DTC memory, and then recheck the DTC.

   Q: Is DTC 86 output? 

   1. YES:  Go to Step 2.
   2. NO:  Replace the seat back assembly of the front seat (LH). Refer to DISASSEMBLY AND ASSEMBLY . Then go to  Step 4.
2. STEP 2. Check the harness for short circuit to ground between the SRS-ECU and the side-airbag module (LH). 
   1. Disconnect SRS-ECU connector C-74.
      Fig 2: Identifying SRS-ECU C-74 Connector Terminal

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   2. Disconnect left hand side-airbag module connector D-15.
      Fig 3: Identifying Side-Airbag Module Connector D-15 (LH)

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   3. 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.
   4. Check for continuity between terminals 21, 22 and body ground.
      • There should be open circuit.
      Fig 4: Measuring Voltage Between Terminals 21, 22 And Body Ground
      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

   Q: Does continuity exist? 

   1. YES:  Go to Step 3.
   2. NO:  Erase the DTC memory, and recheck if any DTC sets. If DTC 86 sets, replace the SRS-ECU. Refer to INSPECTION  . Then go to  Step 4.
3. STEP 3. Check the harness wires for short circuit to ground between SRS-ECU connector C-74 (terminal No.21 and 22) and side-airbag module (LH) connector D-15 (terminal No.1 and 2). 
   Fig 5: Identifying SRS-ECU Connector C-74

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   Fig 6: Identifying Side-Airbag Module Connector D-15 (LH)

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

   Q: Are the harness wires for short circuit to ground between SRS-ECU connector C-74 (terminal No.21 and 22) and side-airbag module (LH) connector D-15 (terminal No.1 and 2) in good condition? 

   1. YES:  Go to Step 4.
   2. NO:  Repair the harness wires between SRS-ECU connector C-74 and side-airbag module (LH) connector D-15. Then go to Step 4.
4. STEP 4. Recheck for diagnostic trouble code. 

   Q: Is DTC 86 output? 

   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 ).