Start the engine, and let it idle. Monitor the ALTERNATOR in the DATA LIST with the HDS. Check if the indicated percentage varies when the headlight switch is on. Does the percentage vary?
YES | - | The alternator signal circuit is OK.■
NO | - | Go to Step 4 .
Turn the headlight switch and ignition switch OFF. Jump the SCS line with the HDS. Disconnect the alternator 4P connector. Disconnect ECM/PCM connector B (24P). Check for coutinuity between body ground and ECM/PCM connector terminal B13. Is there continuity?
YES | - | Repair short in the wire between the ECM/PCM (B13) and the alternator.■
NO | - | Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM / PCM .■