Inspection Procedure 2: Power Supply Circuit System: 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)

1. STEP 1. Power supply fuse check. 

   Q: Is the fuse in good condition? 

   • YES:  Go to Step  3.
   • NO:  Go to Step 2
2. STEP 2. Check for a blown fuse. 
   1. Replace the fuse.
   2. Turn the ignition switch to the "ON" position, wait for at least one minute and then turn the switch off.
   3. Check the fuse.

      Q: Is the fuse in good condition? 

      • YES:  Go to Step 3.
      • NO:  Repair the wiring harness between the C-313 ETACS-ECU connector terminal No. 4/2 and the C-36 SRS-ECU connector terminal No. 61/62, and replace the power supply fuse.
3. STEP 3. Resistance measurement at the C-37 SRS-ECU connectors 
   1. 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-37 SRS-ECU connectors.
      Fig 1: Turning Lock Lever

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   2. Take the measurements below at the C-37 wiring harness side connector.
      • Continuity between C-37 wiring harness side connector terminal No. 17 and body ground

        OK: Continuity (Less than 2 ohms) 

        Q: Is the check result normal? 

        • YES:  Go to Step 4.
        • NO:  Repair the wiring harness between the C-37 SRS-ECU connector terminal No. 17 and the ground.
          Fig 2: Checking Continuity Between C-37 Wiring Harness Side Connector Terminal No. 17 & Body Ground

          Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
4. STEP 4. Measure the voltage at the C-36 SRS-ECU connector. 
   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-36 SRS-ECU connector.
   3. Connect the negative battery terminal.
   4. Ignition switch: ON
      Fig 3: Turning Lock Lever

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   5. Take the measurements below at the C-36 harness side connector.
      • Voltage between terminal No. 61, 62 and body ground

        OK: 9 V or more 

        Q: Is the measured voltage within the specified range? 

        • YES:  Go to Step  6.
        • NO:  Go to Step 5.
          Fig 4: Measuring Voltage Between Terminal No. 61, 62 & Body Ground

          Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
5. STEP 5. Check the harness for open circuit between SRS-ECU connector C-36 (terminal No. 61 and 62) and the ETACS-ECU connector C-313 (terminal No. 4 and 2). 
   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-36 SRS-ECU connector.
   3. Disconnect the ETACS-ECU connector C-313.
      Fig 5: Turning Lock Lever

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   4. Check for continuity between the following terminals. It should be less than 2 ohms.

      < Fuse No. 12> 

      • SRS-ECU connector C-36 (terminal No. 62) and the ETACS-ECU connector C-313 (terminal No. 2)

      < Fuse No. 18> 

      • SRS-ECU connector C-36 (terminal No. 61) and the ETACS-ECU connector C-313 (terminal No. 4)
        Fig 6: Checking Continuity Between SRS-ECU Connector C-36 Terminals & ETACS-ECU Connector C-313 Terminals

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

        Q: Does continuity exist? 

        • YES:  Replace the ETACS-ECU (Refer to ETACS-ECU ).
        • NO:  Repair the harness wire between SRS-ECU connector C-36 and the ETACS-ECU connector C-313.
6. STEP 6. Retest the system 

   Q: Is the communication between scan tool and SRS-ECU possible? 

   • YES:  Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
   • NO:  Replace SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU)  ).