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)

STEP 1. Power supply fuse check.
Q: Is the fuse in good condition?
- YES: Go to Step 3.
- NO: Go to Step 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-30 SRS-ECU connector terminal No. 61/62, and replace the power supply fuse.
STEP 3. Resistance measurement at the C-122 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-122 SRS-ECU connectors.
  
  Fig 1: Turning Lock Lever
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
2. Take the measurements below at the C-122 wiring harness side connector.
  - Continuity between C-122 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-122 SRS-ECU connector terminal No. 17 and the ground.
      
      Fig 2: Checking Continuity Between C-122 Wiring Harness Side Connector Terminal No. 17 And Body Ground
      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 4. Measure the voltage at the C-30 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-30 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-30 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: Checking Voltage Between Terminal No. 61, 62 And Body Ground
      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 5. Check the harness for open circuit between SRS-ECU connector C-30 (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-30 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-30 (terminal No. 62) and the ETACS-ECU connector C-313 (terminal No. 2)
  <Fuse No. 18>
  - SRS-ECU connector C-30 (terminal No. 61) and the ETACS-ECU connector C-313 (terminal No. 4)
    
    Fig 6: Checking Continuity Between SRS-ECU Connector C-30 Terminal No. 62 And ETACS-ECU Connector C-313 Terminal No. 2
    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-30 and the ETACS-ECU connector C-313.
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) ).