Alternator: Testing and Inspection

GENERATOR ON VEHICLE TESTING

CAUTION:To prevent damage to the generator, do not make jumper wire connections except as directed.

CAUTION:Do not allow any metal object to come in contact with the housing and the internal diode cooling fins with key on or off. A short circuit will result and burn out the diodes.
NOTE:Battery posts and cable clamps must be clean and tight for accurate meter indications.
1. Turn OFF all lamps and electrical components.

2. Place the vehicle in N (Neutral) and apply the parking brake.

3. Perform the following component tests.

Load Test

1. Switch the battery tester to the ammeter function.

2. Connect the positive and negative leads of the battery tester to the corresponding battery terminals.

3. Connect the current probe to the generator B+ output lead (B/O) wire.

4. With the engine running at 2,000 rpm, adjust the battery tester load bank to determine the output of the generator. See Component Tests and General Diagnostics.

No Load Test

1. Switch the battery tester to the voltmeter function.

2. Connect the voltmeter positive lead to the generator B+ terminal and the negative lead to ground.

3. Turn all electrical accessories off.

4. With the engine running at 2,000 rpm, check the generator output voltage. The voltage should be between 13.0 and 15.0 volts. If not, see Component Tests and General Diagnostics.