Alternator Control Circuit Troubleshooting
Alternator Control Circuit Troubleshooting1. Check for proper operation of the electrical load detector (ELD) by checking that the malfunction indicator lamp (MIL). If a DTC is present, diagnose and repair the cause before continuing with this test.
2. Disconnect the alternator 4P connector from the alternator.
3. Start the engine, and turn on the headlights to high beam.
4. Measure the voltage between the alternator 4P connector terminal No. 2 and the positive terminal of the battery.
Is the resistance 1 V or less?
YES - Go to step 5.
NO - Go to step 8.
5. Turn off the headlights and ignition switch.
6. Disconnect engine control module (ECM) connector C (31P).
7. Check for continuity between the ECM connector C terminal No. 2 and body ground.
Is there continuity?
YES - Repair a short to ground in the wire between the alternator and the ECM.
NO - Check that the terminals are firmly seated at the connectors. If OK, substitute a known-good PCM, and recheck. If prescribed voltage is now available, replace the original ECM.
8. Turn off the headlights and ignition switch.
9. Disconnect ECM connector C (31P).
10. Check for continuity between the ECM connector C terminal No. 2 and alternator 4P connector terminal No. 2.
Is there continuity?
YES - Repair the alternator.
NO - Repair an open in the wire between the alternator and the ECM.