GM Service Manual Online
For 1990-2009 cars only

The standard generator used is the CS-144 with an output rating of 140 Amps at 2000 engine RPM. The CS stand for Charging System and the 144 denotes the outside diameter of the stator laminations in millimeters. CS series generators have integral voltage regulators.

Output ratings are stamped on the front mounting lugs. A centrifugal fan mounted next to the pulley pulls air through the slip ring end (SRE) frame for cooling. No periodic maintenance on the generator is required.

The generator uses a solid state regulator that is mounted internally. All regulator components are enclosed in a solid mold, and this unit, along with the brush holder assembly, is attached to the SRE frame. To help stabilize engine idle speed during changes in electrical load demand, the regulator adjusts system voltage gradually over a period of a few seconds to allow the generator to accept system load. The regulator voltage setting cannot be adjusted.

The regulator in the CS-144 limits the system voltage by controlling the rotor field current. When the field current is ON, the regulator is actually switching the field current on and off at a fixed frequency of about 400 cycles per second. By varying the overall on-off time, the correct average field current for proper system voltage control is obtained. At high speeds, the on-time may be 10 percent and the off-time 90 percent. At low speeds, the off-time may be 10 percent and the on-time 90 percent. The regulator will adjust system voltage over a period of a few seconds to assist stabilizing engine idle.

A capacitor, or condenser, mounted in the end frame protects the rectifier bridge from high voltages, and suppresses radio noise.

The CS-144 features a non-replaceable sealed ball bearing in the pulley (drive) end frame. The SRE frame contains a roller bearing with lifetime lubrication. The inner race of this bearing is pressed onto the rotor shaft.