Generator On-Vehicle Tests

NOTE: Battery posts and cable clamps must be clean and tight to ensure accurate meter indications.

When performing charging system tests, turn off all lamps and electrical components. Place transmission in NEUTRAL and apply parking brake.

Generator Load Test
1. Switch Alternator, Regulator, Battery, and Starter Tester (ARBST) to the ammeter function.
2. Connect the positive and negative leads of ARBST to the battery.
3. Connect the current probe to the generator B+ output lead, circuit 38 (BK/O).

35/90 Amp Generator:

45/110 Amp Generator:

58/120 Amp Generator:

4. With the engine running at 2000 RPM, adjust ARBST load bank to determine the output of the generator. Compare generator output with the graphs. If not, refer to Symptom Chart for diagnostic procedures. Symptom Related Diagnostic Procedures

No-Load Test
1. Switch ARBST to the voltmeter function.
2. Connect the 73 Digital Multimeter 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 2000 RPM, check the generator output voltage. The voltage should be between 13.0 and 15.0 volts. If not, refer to Symptom Chart for diagnostic procedures. Symptom Related Diagnostic Procedures