Generator On-Vehicle Tests

GENERATOR ON-VEHICLE TESTS

CAUTION:
- To prevent damage to the generator, do not make jumper wire connections except as directed.
- Do not allow any metal object to come in contact with the housing and the internal diode cooling fins with the key on or off. A short circuit will result and burn out the diodes.

NOTE:
- The battery posts and cable clamps must be clean and tight for accurate meter indications.
- Refer to the battery tester manual for complete directions on checking out the charging system.

1. Turn off all lamps and electrical components.
2. Place the vehicle in NEUTRAL and apply the parking brake.
3. Carry out the Load Test and No-Load Test according to the following component tests:

Generator On-Vehicle Test - Load Test
1. Switch the tester to the ammeter function.
2. Connect the positive and negative leads of the tester to the corresponding battery terminals.
3. Connect the current probe to the generator B+ output terminal, circuit 1119 (RD) (upper)/circuit 2037 (RD) (lower).

75/120 Amps (Lower):

95/140 Amps (Upper):

4. NOTE: Make sure to disconnect the generator that is not being tested.

With the engine running at 2,000 rpm, adjust the tester load bank to determine the output of the generator. The generator output should be at or greater than the applicable graphs. If not, refer back to the pinpoint test or GO to Symptom Chart for the diagnostic procedures. Pinpoint Tests Dual Generators

Generator On-Vehicle Test - No-Load Test
1. Switch the tester to the voltmeter function.
2. Connect the positive voltmeter lead to the generator B+ output terminal, circuit 1119 (RD) (upper)/circuit 2037 (RD) (lower) and the negative voltmeter lead to ground.
3. Turn all of the electrical accessories off.
4. With the engine running at 2,000 rpm, check the generator output voltage. The voltage should be between 13.2 and 15.5 volts. If not, refer back to the pinpoint test or GO to Symptom Chart for the diagnostic procedures. Pinpoint Tests Dual Generators