GM Service Manual Online
For 1990-2009 cars only

Charging System Description and Operation W/O Generator/Battery Control Module

Generator

The AD-230 and AD-244 generators are non-repairable. They are electrically similar to earlier models. The generators feature the following major components:

    • The delta stator
    • The rectifier bridge
    • The rotor with slip rings and brushes
    • A conventional pulley
    • Dual internal fans
    • A voltage regulator

The pulley and the fan cool the slip ring and the frame.

The AD stands for air-cooled dual internal fan; the 2 is an electrical design designator; the 30/44 denotes the outside diameter of the stator laminations in millimeters, over 100 millimeters. The generators is rated at 102 and 130 amperes respectively.

The generator features permanently lubricated bearings. Service should only include the tightening of mounting components. Otherwise, the generator is replaced as a complete unit.

Regulator

The voltage regulator controls the field current of the rotor in order to limit system voltage. The regulator switches the current ON and OFF at a rate of 400 cycles per second in order to perform the following functions:

    • Radio noise control
    • Obtain the correct average current needed for proper system voltage control

At high speeds, the on-time may be 10 percent with the off-time at 90 percent. At low speeds, the on-time may be 90 percent and the off-time 10 percent.

Auxiliary Battery Charging

The auxiliary battery is charged in the same manner as the primary battery with the ignition switch in the run position and the engine running. The system contains the following components:

    • Auxiliary battery.
    • Auxiliary battery relay.
    • Mega fuse.
    • Junction block battery cable.
    • Associated wiring.

The auxiliary battery relay coil is energized with the engine running through the fuse block and wiring, thus closing the relay contacts which allow the battery to be charged from the vehicle's generator via the battery junction block. The auxiliary battery relay is permanently grounded so any time the ignition switch is in the run position the relay will be energized.

The auxiliary battery is only used for accessories and is not part of the vehicle starting system. However if the primary battery fails and in need of an jump start, follow the service information for Jump Starting In Case Of Emergency using appropriate battery jumper cables.

Charging System Indicator

The IPC illuminates the charge indicator in the message center when the following occurs:

    • The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the PCM requesting illumination.
    • The IPC determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the body control module (BCM) indicating the system voltage.
    • The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.
    • The ignition is on, with the engine off.