GM Service Manual Online
For 1990-2009 cars only

The generator provides voltage to operate the vehicles electrical system and to charge the vehicles battery. A magnetic field is created when current flows through the rotor.


Object Number: 63635  Size: SH

This field rotates as the rotor is driven by the engine, creating an AC voltage in the stator windings. The AC voltage is converted to DC voltage by the rectifier bridge and is supplied to the electrical system at the battery terminal.


Object Number: 159242  Size: SH

The operation of the charging system is monitored by the PCM. The PCM monitors the charging system loads and adjusts the idle speed accordingly. The PCM also sends information to the Instrument Panel Cluster (IPC) when the charging system is inoperative and tells the IPC to illuminate the volts telltale lamp.

The PCM supplies 5.0V through the L circuit to the generator. If the generator becomes inoperative, the PCM can detect the fault through the L circuit and tell the IPC to illuminate the volts telltale lamp.