Alternator FR Signal Circuit Troubleshooting

Alternator FR Signal Circuit Troubleshooting

1. Start the engine, and let it idle.

2. Monitor the ALTERNATOR in the DATA LIST with the HDS.

3. Check if the indicated percentage varies when the headlight switch is turned on.

Does the percentage vary?
YES - The alternator signal circuit is OK.

NO - Go to step 4.


4. Turn the headlight switch and ignition switch to LOCK (0).

5. Jump the SCS line with the HDS.

6. Disconnect the alternator 4P connector.

7. Disconnect ECM connector B (44P).

8. Check for continuity between body ground and ECM connector terminal B43.

Is there continuity?
YES - Repair short in the wire between the ECM (B43) and the alternator.

NO - Reconnect all connectors, and update the ECM if it does not have the latest software, ECM/PCM Update or substitute a known-good ECM, Reading and Clearing Diagnostic Trouble Codes then recheck. If the symptom/indication goes away and the ECM was updated, troubleshooting is complete. If the symptom/indication goes away and the ECM was substituted, replace the original ECM. Service and Repair