GM Service Manual Online
For 1990-2009 cars only

The charging system of this vehicle is the KDAC AD237 type. The number denotes the outer diameter in millimeters of the stator lamination.

The AD type generators are equipped with a new type of internal regulator that incorporates a diode trio. A delta stator, a rectifier bridge, and a rotor with slip rings and brushes are electrically similar to earlier generators. A conventional pulley and fan are used. There is no test hole.

Unlike the three-wire generators, the AD237 may be used with only two connections: The "L" and "F" terminals are connected to the engine control module (ECM).

As with other charging systems, the charge indicator lamp is controlled by the ECM when the ignition switch is turned to ON and goes out when the engine is running. If the charge indicator lamp is ON with the engine running, a charging system defect is indicated.

This indicator light will glow at full brilliance for several kinds of defects as well as when the system voltage is too high or too low.

The regulator voltage setting varies with temperature and limits the system voltage by controlling rotor field current.