Principles of Operation

The generator on this vehicle has a built-in voltage regulator set point. The generator determines optimal charging system voltage based on temperature. The generator has a communication line (GEN MON) indicating the generator operating duty cycle (including the generator load and error conditions) to the powertrain control module (PCM). The GEN MON circuit is a pulse width modulated (PWM) signal. The GEN MON communication line is also used for fault indication. If there is an error condition, the PCM sends a signal to the instrument cluster (using the standard corporate protocol [SCP] bus) to turn on the charging system warning indicator. The generator has an I terminal which is used for initially turning on the generator when the engine is started. The generator also has a dedicated battery sense terminal (A terminal), which is used to sense the battery voltage.

This is a System 3 charging system, which uses the GEN MON line to monitor the charging system through the PCM and includes a PCM-controlled I (ignition) circuit to the generator. System 3 charging systems are virtually identical in design and therefore, share the same diagnostics.