Undercharged Battery
- With ignition switch ON connect a voltmeter from alternator "BAT" terminal to ground, then from No. 1 terminal to ground, (see illustration) and No. 2 terminal to ground. A zero reading indicates an open between connection and battery. An open No. 2 lead will cause uncontrolled voltage. This may cause overcharge, and possible damage to accessories. Opens in this circuit may be between terminals at the crimp between harness wire and terminal, or in wire.
NOTE: If above checks are satisfactory proceed as follows.
- Disconnect battery ground cable. Connect an ammeter in the circuit at the "BAT" terminal of alternator. Reconnect battery ground cable. Turn on all available accessories. Connect a carbon pile across battery. Operate engine at moderate speed and adjust carbon pile as required to obtain maximum current output. If ampere output is within 10% of rated output as stamped on alternator frame, alternator is not defective. If output is not within 10% of rated output, ground the field winding by inserting a screwdriver into test hole (see illustration).CAUTION: Tab is within 3/4" of casting surface, do not force screwdriver deeper than one inch into end frame.
- Operate engine at moderate speed as required and adjust carbon pile for maximum output. If output is now within 10% of rated output with fields grounded, regulator is defective and requires replacement. If output is still not within 10% of rated output, check field winding, diode trio, rectifier bridge, and stator.