Alternator: Description and Operation

CIRCUIT DESCRIPTION

I Circuit
The I (ignition) circuit:
- Turns the voltage regulator on when the ignition switch is in RUN position.
- Turns the charge warning indicator ON if there is a problem in the charging system.

A Circuit
The A (battery sense) circuit:
- Senses the battery voltage. The voltage regulator uses this to determine the generator output.
- Supplies current to the generator field coil.
- Is always HOT.
- Is protected by a fuse in the power distribution box.

S Circuit
The S (stator) circuit:
- Is used by the voltage regulator to sense the generator (stator) output.
- Voltage is typically one-half of the battery voltage when the Generator (GEN) is operating.
- Voltage is used by the voltage regulator to turn off the warning indicator.

NOTE: If the S circuit is open or disconnected, the charge warning indicator will turn on, even if the Generator (GEN) is operating normally.

The charging warning indicator will turn on if the S circuit voltage is zero. The warning indicator will turn off if the S circuit voltage is greater than 5 volts.

The set voltage will vary with temperature and is typically higher in the winter than summer, allowing for better battery charging.