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Home >> Mitsubishi >> 2005 >> Galant L4-2.4L (4G69) >> Repair and Diagnosis >> Brakes and Traction Control >> Antilock Brakes / Traction Control Systems >> Testing and Inspection >> Symptom Related Diagnostic Procedures >> Anti-Lock Braking System (ABS) >> Inspection Procedure 2

Inspection Procedure 2

INSPECTION PROCEDURE 2: Power Supply Circuit System






CIRCUIT OPERATION
^ The ABS-ECU is energized by the ignition switch (IG1) through multi-purpose fuse 23 and the ABS-ECU terminal 20.
^ If the power supply to the ABS-ECU has failed, scan tool (MUT-III Sub Assembly) will not be able to communicate with it.

TROUBLESHOOTING HINTS (The most likely causes for this case:)
^ Damaged wiring harness or connector
^ Defective battery
^ Charging system failed
^ Malfunction of the hydraulic unit (integrated with ABS-ECU)

DIAGNOSIS
Required Special Tools:
^ 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
^ MB991970: ABS Check Harness

STEP 1. Measure the voltage at ABS-ECU connector A-02.





1. Disconnect the connector A-02, and connect special tool ABS Check Harness (MB991970) to the wiring harness-side connector.

NOTE: Do not connect special tool ABS Check Harness (MB991970) to the ABS-ECU.

2. Turn the ignition switch to the ON position.
3. Measure the voltage between terminal 20 and ground. It should measure approximately 12 volts (battery positive voltage).
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 3.
NO: Go to Step 2.

STEP 2. Check ABS-ECU connector A-02, junction block connectors C-214, C-215 and ignition switch connector C-308 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





^ ABS-ECU connector A-02





^ Junction block connectors C-214 and C-215





^ Ignition switch connector C-308
Q: Are the connectors and terminals in good condition?
YES: An open or short circuit may be present in the power supply line to the ABS-ECU. Repair the wiring harness between ABS-ECU connector A-02 terminal 20 and ignition switch connector C-308 terminal 4. Then go to Step 8.
NO: Repair or replace the damaged component(s). Then go to Step 8.

STEP 3. Measure the resistance at ABS-ECU connector A-02.





1. Disconnect the connector A-02, and connect special tool ABS Check Harness (MB991970) to the wiring harness-side connector.

NOTE: Do not connect special tool ABS Check Harness (MB991970) to the ABS-ECU.

2. Measure the resistance between terminal 2, 18 and ground. It should be 2 ohms or less.
Q: Is the measured resistance 2 ohms or less?
YES: Go to Step 5.
NO: Go to Step 4.

STEP 4. Check ABS-ECU connector A-02 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Is ABS-ECU connector A-02 damaged?
YES: Repair or replace the damaged component(s). Then go to Step 8.
NO: An open circuit may be present in the ground circuit. Repair the wiring harness between ABS-ECU connector A-02 terminals 2, 18 and the body ground. Then go to Step 8.

STEP 5. Check the battery.
Check the battery.
Q: Is the battery in good condition?
YES: Go to Step 6.
NO: Charge or replace the battery. Then go to Step 8.

STEP 6. Check the charging system.
Check the charging system.
Q: Is the charging system in good condition?
YES: Go to Step 7.
NO: Repair or replace the charging system component(s). Then go to Step 8.

STEP 7. Retest the system.
Q: Can the ABS-ECU communicate with the scan tool (MUT-III Sub Assembly)?
YES: It can be assumed that this malfunction is intermittent.
NO: Replace the ABS-ECU. Then go to Step 8.

STEP 8. Retest the system.
Q: Can the ABS-ECU communicate with the scan tool (MUT-III Sub Assembly)?
YES: The procedure is complete.
NO: Go to Step 1.





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