Alternator Lamp/Indicator: Description and Operation

OPERATION
The alternator warning indicator is connected across the terminals of a 500-ohm resistor at the instrument cluster. Current passes through the indicator when the ignition switch is in "RUN" and there is no voltage at terminal S. When voltage at terminal S rises to a preset value, the regulator switching circuits stop the flow of current into terminal I, and the indicator turns off.

System voltage is sensed at Regulator terminal A. The regulator switching circuits turn the warning indicator on to indicate a system fault if terminal A voltage is excessively high or low, or if the voltage at terminal S is below a preset value.