GM Service Manual Online
For 1990-2009 cars only

Generator Description and Operation CS144 Generator

The CS144 generator uses an internal, temperature compensated voltage regulator with a built in fault detection, a delta wound stator, a rectifier bridge, and a rotor with slip rings and brushes. The CS144 has an external fan that provides cooling for the internal components. The voltage regulator incorporates a Load Response Control (LRC) to provide additional loads and reduce fluctuations in the output voltage The CS144 has three wiring connections, (1) the output (BAT) terminal connection, (2) the (L) terminal connection, and (3) the (S) terminal connection.

The output (B) terminal connection is connected directly to B+ voltage and has 12 volts all the time. This terminal provides voltage and current to charge the battery and operate the vehicle electrical components. This terminal is necessary at start up because it provides initial field current from the battery to begin generator operation.

The (L) terminal is connected to the charge indicator circuit which is grounded through the voltage regulator whenever the generator is stopped or the charging voltage is too high or too low.

The (S) terminal is connected to the voltage sense circuit that is connected to another point in the (B+) circuit for the normal voltage control and is hot all the time. If this circuit is disconnected the generator reverts to internal voltage for control. High resistance in this circuit may cause the generator to produce an incorrect or erratic system voltage.

Generator Description and Operation Valeo A13VI+ Generator

The Valeo A13VI+ generator is rated for a maximum output of 105 amperes. The stator is a "Y" wound design and the integral Motorola regulator incorporates a Load Response Control (LRC) function that "ramps-up" loads. This feature provides a gradual loading of the charging system when large, transient electrical loads are encountered. Cooling is provided by a Dual Internal Fan (DIF).

Generator Description and Operation U Van Electrical

Charging

The generator provides voltage to operate the vehicle's electrical system and to charge its battery. A magnetic field is created when current flows through the rotor. This field rotates as the rotor is driven by the engine, creating an AC voltage in the stator windings. The AC voltage is converted to DC by the rectifier bridge and is supplied to the electrical system at the battery terminal.

The generator's digital regulator uses digital techniques to supply the rotor current and thereby control the output voltage. The rotor current is proportional to the width of the electrical pulses supplied by the digital regulator. When the ignition switch is placed in RUN, voltage is supplied to terminal L turning on the digital regulator. Narrow width pulses are supplied to the digital rotor, creating a weak magnetic field. When the engine is started, the digital regulator senses generator rotation by detecting the AC voltage at the stator through an internal wire. Once the engine is running, the digital regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation.

The Powertrain Control Module (PCM) controls the CHARGE indicator bulb with a solid state lamp driver. The lamp driver turns on the bulb whenever it detects an undervoltage, overvoltage or stopped generator.