Alternator: Testing and Inspection

Fig. 1 Alternator terminal location. Typical:

1. With ignition switch off, connect voltmeter between alternator terminal ``B'' and ground, Fig. 1, and observe reading. Reading should be battery voltage.
2. Connect voltmeter between alternator terminal L and ground and observe reading. Voltmeter should read zero volts. If not, replace alternator.
3. Turn on ignition, then connect voltmeter between alternator terminal L and ground. Observe reading. Voltmeter should read 1-3 volts. If voltmeter reads zero volts, the alternator, regulator and/or the wiring harness is defective. If voltmeter reads close to battery voltage, proceed to next step.

Fig. 2 Location of test terminal F. Typical:

4. Ground F terminal at rear of alternator, Fig. 2, then observe L terminal voltage. If voltage reads significantly less than battery voltage, replace regulator. If voltage reads at or near battery voltage, replace alternator.