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Test A: Charging System Test

  1. Reviewing the description and operation information will help determine the correct symptom diagnostic procedure when a malfunction exists and will also help determine if the condition described by the customer is normal operation. See DESCRIPTION & OPERATION  . If review was performed, go to next step.
  2. The battery must be above a 70 percent state of charge. If battery inspection test was performed, go to next step. If battery inspection test was not performed, see BATTERY TESTING & INSPECTION  under ON-VEHICLE TESTING.
  3. Install a scan tool. Start the engine. Turn ON the following accessories:
    • Headlights - high beams.
    • A/C on MAX.
    • Blower fan - ON high.
    Increase engine speed to 2500 RPM. Measure the voltage between the generator output terminal and ground. Voltage should 12.0-15.5 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step  5 .
  4. Turn OFF all accessories. Turn OFF the ignition. Connect a carbon pile tester to the vehicle. Connect an inductive ammeter probe to the output circuit of the generator. Start the engine. Increase engine speed to 2500 RPM. Adjust the carbon pile as necessary in order to obtain maximum current output of greater than or equal to 56-amps. If amperage is as specified, go to step  15 . If amperage is not as specified, go to step  6 .
  5. If the voltage measured is greater than 15.5 volts, go to step  9 . If the voltage measured is not greater than 15.5 volts, go to next step.
  6. Turn OFF the accessories. Turn ignition switch to OFF position. Disconnect generator harness connector. Turn ON the ignition, with the engine OFF. Measure voltage between ground and generator harness connector terminal No. 2 (Red/White wire). If battery voltage exists, go to next step. If voltage is not as specified, go to step  11 .
  7. Maintain engine speed at 2500 RPM and continue to operate generator at load test value. Using a DVOM, measure voltage drop between battery positive terminal and the generator output terminal. If voltage drop is 0.5 volt or less, go to next step. If voltage drop is greater than 0.5 volt, go to step  12 .
  8. Maintain the engine speed at 2500 RPM. Measure the voltage drop between the battery negative terminal and the generator metal housing. If voltage drop is 0.5 volt or less, go to next step. If voltage drop is greater than 0.5 volt, go to step  13 .
  9. Test sense circuit located between generator harness connector terminal No. 3 (White wire) and 5-amp ALT "S" fuse located in underhood fuse block for a high resistance or open. See WIRING DIAGRAMS  . If no problem exists, go to next step. If problem exists, repair as necessary. After repair, go to step  15 .
  10. Inspect generator harness connector for poor connections. If problem exists, repair as necessary. After repair, go to step  15 . If no problem exists, go to step  14 .
  11. Repair the high resistance or open in the generator turn on signal circuit located between generator harness connector terminal No. 2 (Red/White wire) and 10-amp GAUGE fuse in instrument panel fuse block. See WIRING DIAGRAMS  and COMPONENT LOCATIONS  . Repair as necessary. After repair, go to step  15 .
  12. Test B+ circuit for a high resistance or open. If problem exists, repair as necessary. After repair, go to step  15 .
  13. Repair high resistance or open in ground circuit of generator. See WIRING DIAGRAMS  . After repair, go to step  15 .
  14. Replace generator. See GENERATOR  under REMOVAL & INSTALLATION. After repair, go to next step.
  15. Operate system to verify repair. If system is not operating correctly, repeat test beginning at step  2 .
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