INSPECTION PROCEDURE 1: Communication with Scan Tool MB991958 is Impossible.: Diagnosis

Required Special Tools: 

• MB991223: Harness Set
• MB991958: Scan Tool (MUT-III Sub Assembly)
  • MB991824: Vehicle Communication Interface (V.C.I.)
  • MB991827: MUT-III USB Cable
  • MB991910: MUT-III Main Harness A (Vehicles with CAN communication system)

1. STEP 1. Using scan toll MB991958, read the MFI system diagnostic trouble code. 
   CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool.

   Use scan tool MB991958 to confirm the MFI system DTC.

   1. Connect scan tool MB991958 to the data link connector.
   2. Turn the ignition switch "ON" to position.
   3. Read the MFI system diagnosis code.
      NOTE: If the scan tool MB991958 cannot communicate with the MFI system, refer to INSPECTION PROCEDURE 2: SCAN TOOL COMMUNICATION WITH PCM IS NOT POSSIBLE or INSPECTION PROCEDURE 2: SCAN TOOL COMMUNICATION WITH PCM IS NOT POSSIBLE. .

   Q: Is an MFI system DTC P0513 output? 

   1. YES:  Refer to DIAGNOSTIC TROUBLE CODE CHART or DIAGNOSTIC TROUBLE CODE CHART .
   2. NO:  Go to Step 2.
      Fig 1: Connecting Scan Tool MB991958 To Data Link Connector

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2. STEP 2. Check the immobilizer-ECU power supply circuit by backprobing. 
   1. Do not disconnect immobilizer-ECU connector C-124.
   2. Turn the ignition switch to the "ON" position.
      Fig 2: Identifying C-124 Connector Terminals

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   3. Measure the voltage between terminal 1 and ground by backprobing.
      • The voltage should measure approximately 12 volts (battery positive voltage).

   Q: Is the measured voltage approximately 12 volts (battery positive voltage)? 

   1. YES:  Go to  Step 5.
   2. NO:  Go to Step 3.
      Fig 3: Measuring Voltage Between Terminal 1 And Ground Backprobing

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3. STEP 3. Check immobilizer-ECU connector C-124 and MFI relay connector B-17X for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Are immobilizer-ECU connector C-124 and MFI relay connector B-17X in good condition? 

   1. YES:  Go to Step 4.
   2. NO:  Repair or replace the component(s). Refer to HARNESS CONNECTOR INSPECTION . Confirm that scan tool MB991958 communicates normally.
      Fig 4: Identifying B-17X Connector Terminals

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      Fig 5: Identifying C-124 Connector Terminals

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4. STEP 4. Check the wiring harness between immobilizer-ECU connector C-124 (terminal 1) and MFI relay connector B-17X (terminal 4). 
   Fig 6: Identifying B-17X Connector Terminals

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   Fig 7: Identifying C-29 & C-124 Connector Terminals

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   NOTE: Also check intermediate connector A-13, C-29, check the wires. If intermediate connector A-13, C-29 are damaged, repair or replace them. Refer to HARNESS CONNECTOR INSPECTION .

   Q: Are the wiring harness between immobilizer-ECU connector C-124 (terminal 1) and MFI relay connector B-17X (terminal 4) in good condition? 

   1. YES:  There is no action to be taken.
   2. NO:  Repair the wiring harness. Confirm that scan tool MB991958 communicates normally.
      Fig 8: Identifying A-13 Connector Terminals

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5. STEP 5. Measure the resistance at immobilizer-ECU connector C-124. 
   1. Do not disconnect immobilizer-ECU connector C-124.
      Fig 9: Identifying ECU Connector C-124

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   2. Measure the resistance between terminal 2 and ground.

   Q: Is the resistance less than 2 ohms? 

   1. YES:  Go to  Step 8.
   2. NO:  Go to Step 6.
      Fig 10: Measuring Resistance Between Terminal 2 And Ground

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6. STEP 6. Check immobilizer-ECU connector C-124 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Is immobilizer-ECU connector C-124 in good condition? 

   1. YES:  Go to Step 7.
   2. NO:  Repair or replace the component(s). Refer to HARNESS CONNECTOR INSPECTION . Confirm that scan tool MB991958 communicates normally.
      Fig 11: Identifying C-124 Connector Terminals

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
7. STEP 7. Check the wiring harness between immobilizer-ECU connector C-124 (terminal 2) and ground. 
   Fig 12: Identifying C-03 & C-124 Connector Terminals

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   NOTE: Also check joint connector C-03, check the wires. If joint connector C-03 is damaged, repair or replace them. Refer to HARNESS CONNECTOR INSPECTION .

   Q: Is the wiring harness between immobilizer-ECU connector C-124 (terminal 2) and ground in good condition? 

   1. YES:  There is no action to be taken.
   2. NO:  Repair the wiring harness. Confirm that scan tool MB991958 communicates normally.
8. STEP 8. Check immobilizer-ECU connector C-124 and PCM connector B-19 for loose, corroded or damaged terminals, or terminal pushed back in the connector. 

   Q: Are immobilizer-ECU connector C-124 and PCM connector B-19 in good condition? 

   1. YES:  Go to Step 9.
   2. NO:  Repair or replace the components). Refer to HARNESS CONNECTOR INSPECTION . Confirm that scan tool MB991958 communicates normally.
      Fig 13: Identifying B-19 Connector Terminals

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      Fig 14: Identifying C-124 Connector Terminals

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9. STEP 9. Check the wiring harness between immobilizer-ECU connector C-124 (terminal 3) and PCM connector B-19 (terminal 13). 
   Fig 15: Identifying B-19 Connector Terminals

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   Fig 16: Identifying C-29 & C-124 Connector Terminals

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   NOTE: Also check intermediate connector C-29, check the wires. If intermediate connector C-29 is damaged, repair or replace them. Refer to HARNESS CONNECTOR INSPECTION .

   Q: Are the wiring harness between immobilizer-ECU connector C-124 (terminal 3) and PCM connector B-19 (terminal 13) in good condition? 

   1. YES:  Go to Step 10.
   2. NO:  Repair the wiring harness. Confirm that scan tool MB991958 communicates normally.
10. STEP 10. Replace the immobilizer-ECU or PCM. 

    Replace the immobilizer-ECU or PCM.

    Q: Did the communication with the scan tool become possible after replacing the immobilizer-ECU or the PCM? 

    1. YES:  Register the password (secret code) and encrypted code HOW TO REGISTER ENCRYPTED CODE .
    2. NO:  Replace the PCM. Then register the password (secret code) and encrypted code (Refer to HOW TO REGISTER ENCRYPTED CODE ).