Operating Test

Ensure battery is fully charged. Connect a 30-volt voltmeter. Turn ignition switch to "ON" position and test as follows:

1. If charge light remains off, disconnect connector from rear of alternator and ground "L" lead wire.
   NOTE: With alternator side "L" terminal grounded, internal short occurs when positive diode is short-circuited.
2. If light remains off, replace indicator bulb and retest. If light is on, reconnect connector. On gasoline models, ground "F" terminal by touching brush with grounded wire. On diesel models, use a screwdriver to ground brush to alternator body. If light stays on, replace IC regulator. If light goes out, repair alternator.
3. If light came on when ignition was turned to "ON" position, start and idle engine. If light is dim, flickers or remains bright, remove and repair alternator. If light went off at idle, run engine at 1500 RPM, and turn headlights on high beam.
4. If charge light is on dim, idle engine, and measure voltage between terminals "B" and "L". If less than .5 volt, alternator is okay. If more than .5 volt, remove and repair alternator.
   NOTE: Terminals "S", "L", "BAT" and "E" are marked on rear cover of alternator.
5. If charge light went off at 1500 RPM with lights on high beam, measure "B" voltage. If more than 15.5 volts, replace IC regulator. If 13-15 volts, idle engine and check indicator light. If off, system is okay. If on, repair alternator.