Alternator: Testing and Inspection

OUTPUT TEST

1. Connect suitable alternator test equipment as per manufacturer's instructions.
2. Switch off all electrical accessories, then start engine and run at 3000 RPM.
3. Adjust load maximum ammeter reading while maintaining voltage of at least 12 volts.
4. If ammeter reading is more than 16 amps below alternator reading, replace regulator and retest.
5. If ammeter reading is still too low, replace alternator.

REGULATOR TEST

1. With tester still connected, turn off all electrical components.
2. Run engine at 3000 RPM until voltage stops rising. If voltage is not 13.5-14.5 volts, replace regulator and repeat test.

DIODE TEST

1. With tester still connected, run engine at 3000 RPM and adjust load according to tester manufacturer's instructions.
2. If meter reads bad, replace alternator.

CURRENT DRAIN TEST

1. Turn off ignition switch, radio and all lights, but leave rear window defogger switch and A/C switches on.
2. Disconnect battery ground cable.
3. Connect test light between ground cable and negative battery terminal.
4. If test light burns brightly, something is switched on or shorted.
5. Locate problem by removing fuses from fuse box one at a time until light goes out.
6. If no faults are found in fused circuits, disconnect cables from non-fused circuits until test light goes out.