Charging Systems: Description

The CS144 (Charging System) series generators have a high amperage output. The 144 designation is the outside diameter of the stator laminations, measured in millimeters. CS series generators include a delta stator, rectifier bridge, and rotor with slip rings and brushes. A built-in regulator incorporates fault detection circuitry. See Fig 1 . A conventional pulley and external fan are used to cool slip ring end frame, rectifier bridge and regulator. Some models are equipped with A13VI generator. Testing is identical.

Generator operates with 3 wire connections and a ground path through the mounting bracket. The first wire connection is the BAT (output) terminal. This terminal must be connected to the battery during operation. The second wire connection is connected from generator terminal "L" internal regulator lamp driver to PCM. This circuit monitors and controls generator operation. The PCM controls indicator light function. The third wire is connected from generator terminal "S" to ALT SENSE fuse (10-amp) in underhood junction block. This provides internal regulator with an external voltage reading. If this circuit is interrupted, regulator will default to internal voltage reading for control.

Regulated voltage varies with temperature. System limits voltage by controlling rotor field current while field current is on. Regulator switches rotor field current on and off at a fixed frequency of 400 cycles per second to help control radio noise. By varying overall on/off time, correct average field current for proper system voltage control is obtained. At high speeds, with lower electrical loads, on-time may be 10 percent. At low speeds, with higher electrical loads, on-time may be as much as 90 percent. Refer to the GENERATOR USAGE/AMP OUTPUT RATING  table.

Fig 1: Charging System Wiring Schematic CS144 Series

Courtesy of GENERAL MOTORS CORP.