Generator Testing

CAUTION
- To prevent damage to the Generator (GEN), 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 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.
- Refer to the Battery Tester Procedure Manual for complete directions on testing the charging system.

1. Turn OFF all lamps and electrical components.
2. Place the vehicle in transmission range NEUTRAL and apply the parking brake.
3. Carry out the Load Test and No-Load Test.


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, Circuit 38 (BK/O).







4. With the engine running at 2000 rpm, adjust Starter, Alternator, Battery, Regulator and Electrical Tester (S.A.B.R.E) load bank to determine the output of the generator. Generator output should be greater than as shown on the graph. If not, refer to Pinpoint Test A. A: Charge Lamp On W/Eng Running (Low Voltage)

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, refer to the Symptom Chart for diagnostic procedures. Symptom Related Diagnostic Procedures