Generator Output Test
- To bench check alternator proceed as follows: Make connections as shown in illustration, except leave carbon pile disconnected. Use a fully charged battery, and a 10 Ohm resistor rated at 6 watts or more between alternator No. 1 terminal and battery. Slowly increase alternator speed and observe voltage. If voltage is uncontrolled with speed and increases above 16 volts, check for a grounded brush lead clip. If brush lead clip is OK replace regulator.
- Connect carbon pile. Operate alternator at moderate peed and adjust carbon pile to obtain maximum output. If output is within 10% of rated output as stamped on alternator frame, alternator is good. If not, ground generator field with a screwdriver. If output is now within 10% of rated output, regulator is defective.
Courtesy of GENERAL MOTORS COMPANY