GM Service Manual Online
For 1990-2009 cars only

The charging system consists of the following components:

    • The battery
    • The generator
    • The regulator
    • The charging system indicator lamp or gauge

The generator supplies electrical power in order to charge the battery and operate the accessories.

The following types of generators are used on these vehicles:

    • The SI-Series
    • The CS-Series

The SI-Series generator can be identified by the 2-terminal regulator connector. The CS-Series generator has a 4-terminal regulator connector.

CS-144 Generator


Object Number: 206216  Size: SH

The CS-144 generator that is equipped with an integral regulator features a high ampere output per pound of weight. The generator does not use a diode trio. The following components are electrically similar to other CS series generators:

    • The deta stator
    • The rectifier bridge
    • The rotor with slip rings and brushes

CS stands for Charging System. 144 indicates the outside diameter of the stator laminations in millimeters. The bearings are sealed with lifetime lubrication in both end frames. No periodic maintenance is required.

21-SI 200 Generator


Object Number: 203654  Size: SH

The 21-SI 200 generator has a solid-state regulator that is equipped with a two-terminal connector that mounts inside the slip ring end frame. The voltage regulator is not adjustable.


Object Number: 203660  Size: SH

The 21-SI 200 generator is equipped with an R terminal in order to operate the auxiliary equipment. The R terminal (3) is located where the I terminal is normally located.

The rotor bearings contain enough grease in order to eliminate periodic lubrication. Two brushes carry current through the two slip rings to the field coil.

The stator windings are assembled on the inside of a laminated core that forms part of the generator frame. A rectifier bridge that connects to the stator winding s contains six diodes. The rectifier bridge electrically changes the stator AC voltages to DC voltage. This DC voltage appears at the generator output BAT terminal. A diode trio that connects to the stator windings supplies the generator field current. A capacitor mounted to the end frame protects the rectifier bridge and diode trio from high voltages. The capacitor also suppresses radio noise.

The generator part number is stamped into the housing behind a mounting flange.