Inspection Procedure 14: Battery Rundown

OPERATION

The exciting currents of the alternator field coil are input into the engine-ECU connector terminal ALTL from the alternator connector terminal.

COMMENTS ON TROUBLE SYMPTOM

The failure could possibly be caused by the failed alternator, defective alternator control system and so on.

PROBABLE CAUSES

Failed battery
Open/short circuit or harness damage in alternator L terminal circuit
Failed alternator
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check battery.

Check battery (Refer to GROUP 54A - Battery - On-vehicle Service - Battery Test).

Q. Is the check result normal?

	Go to Step 2.

	Replace the battery.

STEP 2. M.U.T.-III diagnosis code

Q. Is diagnosis code set?

	Inspection chart for diagnosis code (Refer to ).

	Go to Step 3.

STEP 3. Perform voltage measurement at alternator connector

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal engine-ECU ALTL line and body earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 5.

	Go to Step 4.

STEP 4. Check harness between engine-ECU connector terminal ALTL and alternator connector terminal.

Check power supply line for open/short circuit.

Q. Is the check result normal?

	Go to Step 5.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 5. Check the trouble symptom.

Q. Does the trouble symptom persist?

	Replace the engine-ECU.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).