GM Service Manual Online
For 1990-2009 cars only

This vehicle uses a 140 ampere CS 144 generator. The 145 ampere generator is only used on vehicles with a rear HVAC (C34). C34 equipped vehicles require a generator with a greater ampere output.

The CS 144 generator uses at least two wire connections and a ground path through the mounting bracket for operation. The battery positive BAT terminal must be connected to a battery. A connection must be made through the indicator lamp or other suitable external resistor to the L terminal of the voltage regulator. Both connections are necessarty in order to turn the unit on at start-up. Three other regulator terminals are available for optional use in vehicle systems. The P terminal is connected to the stator and may be connected to a tachometer or other device. The I/F terminal provides an alternate method for turning on the generator without going through the indicator light or other external resistor. It is often used in parallel with the L terminal connection. The S terminal may be used to sense electrical system voltage elsewhere on the vehicle for voltage control. If the S terminal is not used, the regulator uses an internal voltage sense for control.

The voltage regulator is temperature compensated and limits the system voltage by controlling rotor field current. To control radio noise, the field current is switched on and off at a fixed frequency of about 400 cycles per second while the field circuit is ON. By varying the on-off time, the voltage regulator is able to maintain the correct average field current for proper system voltage. At high speeds, the field current may be on only 10 percent of the time that the vehicle is in operation. At lower speeds, with high electrical loads, the field current may be on 90 percent of the time. These generators do not require any periodic maintenance. Both are serviced as complete assemblies.