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Test C: System Overcharges

  1. Check For Fault Codes In PCM

    Connect New Generation Star (NGS) tester to Data Link Connector (DLC). Turn ignition on. Using NGS tester, perform Powertrain Control Module (PCM) self-test. If no DTCs are retrieved, go to next step. If any Diagnostic Trouble Codes (DTC) are retrieved, perform appropriate test in accordance with DTC retrieved. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

  2. Check Battery Voltage

    Start engine. With engine running and all accessories turned off, measure the voltage at the battery while varying the engine RPM. Is the voltage greater than 15.5 volts? If yes, go to next step. If no, go to step  4 .

  3. Check For Voltage Drop In "A" Circuit (Orange/Light Blue Wire)

    Turn ignition off. Disconnect generator 3-pin connector. Measure the voltage between the generator connector terminal No. 3 (Orange/Light Blue wire) and ground. See Figure . Is the voltage within 0.5 volt from battery voltage? If yes, reconnect generator 3-pin connector and go to next step. If no, repair high resistance in Orange/Light Blue wire. Test system for normal operation.

  4. Check Generator PIDs

    Turn ignition on. Enter the MONITOR PCM PIDS diagnostic mode on NGS tester. Monitor the PID GEN_COM in the PCM. Did the GEN_COM PID read YES? If yes, go to next step. If no, go to step  6 .

  5. Check Generator Integrity

    Disconnect generator 3-pin connector. Start engine. If the generator communication lines are disconnected, the generator will self excite if it is operated at approximately 2000 engine RPM for a momentary period of time. It will then operate in a default mode at approximately 13.5 volts until the engine is turned off. With the engine running at approximately 2000 RPM, measure the battery voltage. Is the battery voltage approximately 13.5 volts? If yes, go to next step. If no, install a new generator. See GENERATOR  under REMOVAL & INSTALLATION. Test system for normal operation.

  6. Check For Correct PCM Operation

    Turn ignition off. Disconnect PCM connector. Check for corrosion and pushed-out pins. Connect any disconnected connectors. Make sure all other system connectors are fully seated. Operate the system and verify the concern is still present. Is the concern still present? If yes, install a new PCM. See COMPUTERIZED ENGINE CONTROLS in appropriate REMOVAL & INSTALLATION article in ENGINE PERFORMANCE. Repeat the PCM self-test. If no, the system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. Clear the DTCs. Repeat the self-test.
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