Inspection Procedure 25

INSPECTION PROCEDURE 25: Generator output voltage is low (approximately 12.3 volts)














CIRCUIT OPERATION

- The ECM [M/T] or the PCM [A/T] controls generator out put current by duty-controlling continuity between the generator G terminal (terminal No. 1) and ground.

TROUBLESHOOTING HINTS (The most likely causes for this charging system:)

- Malfunction of the charging system.
- Short circuit in harness between generator G terminal and ECM [M/T] or PCM [A/T].
- ECM failed. [M/T]
- PCM failed. [A/T]

DIAGNOSIS

Required Special Tool:

- MB991923: Powertrain ECU Check Harness

STEP 1. Measure the voltage at ECM [M/T] or PCM [A/T] connector B-22 by using check harness special tool MB991923.









(1)Disconnect all ECM [M/T] connectors or PCM [A/T] connectors.
Connect the check harness special tool MB991923 between the separated connectors.
(2)Start the engine and run at idle.





(3)Measure the voltage between terminal No. 132 and ground.
NOTE:
Vehicle for Canada, the headlight, taillight, etc. remain lit even when the lighting switch is in "OFF" position but this is no problem for checks.

1. Engine: warming up

2. Radiator fan: stopped

3. Headlight switch: OFF to ON

4. Rear defogger switch: OFF to ON

5. Stoplight switch: OFF to ON

- Voltage rises.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the measured voltage within the specified range?

YES Go to Step 2.

NO Replace the generator. Then confirm that the malfunction symptom is eliminated.

STEP 2. Check harness connector B-22 at ECM [M/T] or PCM [A/T] connector and harness connector B-120 at generator connector for damage.









Q. Is the harness connector in good condition?

YES Go to Step 3.

NO Repair or replace it. Harness Connector Inspection.
Then confirm that the malfunction symptom is eliminated.

STEP 3. Check for open circuit and short circuit to ground and harness damage between generator connector B-120 (terminal No. 1) and ECM [M/T] or PCM [A/T] connector B-22 (terminal No. 132).









Q. Is the harness wire in good condition?

YES Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Immobilizer System.
Then confirm that the malfunction symptom is eliminated.

NO Repair it. Then confirm that the malfunction symptom is eliminated.