Alternator: Description and Operation

GENERATOR

Generator:

The PCM controls generator charging by supplying 5 volts on the generator L-terminal circuit whenever the ignition is turned On or the engine is running. This control voltage is necessary for the generator to charge once the generator begins to spin. With the ignition On, engine Off, the generator will ground the generator L-terminal circuit through a resistor. When the engine is started and the generator begins to charge, the generator will open the circuit (still using the 5 volt control voltage) signaling to the PCM that the generator is charging.

The generator will pulse width modulate ignition voltage to the PCM on the generator F-terminal circuit which relays generator duty cycle or electrical load.

CHARGE TELLTALE - If the voltage at the PCM generator L-terminal is low or if the generator F-terminal duty cycle is too low when the engine is running, the PCM will send a message to the I/P cluster over the Class II link to turn On the Charge telltale.