Generator "L" Light Circuit

The control module controls generator charging by supplying a voltage (5 volts or 12 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 control voltage) signaling to the ECM that the generator is charging. If the voltage at the control module generator "L" terminal is low when the engine is running, the control module will send a message to the instrument panel cluster to turn on the charge telltale.