Charging System Circuit Description

The generator output circuit is connected to battery positive voltage through a fusible link wire at the starter B terminal. This circuit is used to charge the battery and supply power to the vehicle electrical systems.

The generator D terminal or sense circuit is supplied battery positive voltage through another fusible link wire from the starter B terminal. This battery voltage signal is used by the voltage regulator as the reference for system voltage control. If this circuit opens or if for any reason supplies less than 10 Volts to the generator sense circuit, the voltage regulator will automatically sense voltage internally, and the generator will operate at a reduced capacity.

The generator L terminal circuit 225 is a discrete circuit to the PCM. The PCM applies ignition voltage to the generator L terminal circuit. A small amount of current flows from this circuit through the generator windings to ground. This creates a magnetic field which starts the generator process. When the generator reaches operating speed and is producing a voltage, a solid state switch for the L terminal circuit in the generator opens and the PCM detects that the initial startup current flow has stopped. The PCM expects to detect low voltage on the L terminal circuit prior to the generator rotating at operating speed and to be at ignition voltage potential when the generator is operating normally.

The generator F terminal circuit 23 is an input to the PCM and indicates the percentage of total capacity that the generator is producing. This signal is detected by the PCM as a duty cycle from the generator and is displayed on the scan tool as a percentage. The PCM monitors the generator output under all conditions to determine if it is functioning normally.