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Home >> Mitsubishi >> 2005 >> Galant L4-2.4L (4G69) >> Repair and Diagnosis >> Accessories and Optional Equipment >> Antitheft and Alarm Systems >> Testing and Inspection >> Symptom Related Diagnostic Procedures >> Inspection Procedures >> Inspection Procedure 1

Inspection Procedure 1

Communication with Scan Tool MB991958 is Impossible

Immobilizer-ECU Power Supply, Ground And PCM Communication Line Circuit Part 1:




Immobilizer-ECU Power Supply, Ground And PCM Communication Line Circuit Part 2:






CIRCUIT OPERATION
The Immobilizer-ECU is energized by the MFI relay when the ignition switch is turned "ON". The PCM transmits a signal from scan tool MB991958 to the immobilizer-ECU as it is. In the same way, a signal from the immobilizer-ECU is also transmitted to scan tool MB991958 as it is.

TECHNICAL DESCRIPTION (COMMENT)
- This malfunction may be caused by a defective immobilizer-ECU, PCM, or a defect in the communication line between the immobilizer-ECU and PCM. If this malfunction appears when the MFI system and scan tool MB991958 can communicate each other, MFI system DTC P0513 will reset.
- If the MFI system is normal, the MFI relay can be determined as normal. In addition, if the MFI system and scan tool MB991958 can communicate each other, the circuits between the data link connector and the PCM can determined as normal.

NOTE: If this malfunction appears, MFI system DTC P0513 will be output.

TROUBLESHOOTING HINTS
- Malfunction of the immobilizer-ECU
- Malfunction of the PCM
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector

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)

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 MFI Diagnosis - Symptom Procedures.

Q: Is an MFI system DTC P0513 output?

YES: Refer to MFI Diagnosis - Diagnostic Trouble Code Chart.

NO: Go to Step 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.




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)?

YES: Go to Step 5.

NO: Go to Step 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?

YES: Go to Step 4.

NO: Repair or replace the component(s). Refer to Harness Connector Inspection. Confirm that scan tool MB991958 communicates normally.










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

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?

YES: There is no action to be taken.

NO: Repair the wiring harness. Confirm that scan tool MB991958 communicates normally.

STEP 5. Measure the resistance at immobilizer-ECU connector C-124.




1. Do not disconnect immobilizer-ECU connector C-124.




2. Measure the resistance between terminal 2 and ground.

Q: Is the resistance less than 2 Ohms?

YES: Go to Step 8.

NO: Go to Step 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?

YES: Go to Step 7.

NO: Repair or replace the component(s). Refer to Harness Connector Inspection. Confirm that scan tool MB991958 communicates normally.




STEP 7. Check the wiring harness between immobilizer-ECU connector C-124 (terminal 2) and ground.

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?

YES: There is no action to be taken.

NO: Repair the wiring harness. Confirm that scan tool MB991958 communicates normally.







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?

YES: Go to Step 9.

NO: Repair or replace the component(s). Refer to Harness Connector Inspection. Confirm that scan tool MB991958 communicates normally.







STEP 9. Check the wiring harness between immobilizer-ECU connector C-124 (terminal 3) and PCM connector B-19 (terminal 13).

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?

YES: Go to Step 10.

NO: Repair the wiring harness. Confirm that scan tool MB991958 communicates normally.

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?

YES: Register the password (secret code) and encrypted code, refer to Antitheft and Alarm Systems/Service and Repair/How To Register Encrypted Code.

NO: Replace the PCM. Then register the password (secret code) and encrypted code (Refer to Antitheft and Alarm Systems/Service and Repair/How To Register Encrypted Code).
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