The AD-237 generator is electrically similar to earlier models. The generator features the following major components:

The pulley and the fan cool the slip ring and the frame.

The AD stands for Air-cooled Dual internal fan; the 2 is an electrical design designator; the 37 denotes the outside diameter of the stator laminations in millimeters, over 100 millimeters. The generator is rated at 125 amperes.

The generator features permanently lubricated bearings. Service should only include tightening of mount components. Otherwise, replace the generator as a complete unit.

The voltage regulator controls the rotor field current in order to limit the system voltage. When the field current is on, the regulator switches the current on and off at a rate of 400 cycles per second in order to perform the following functions:

At high speeds, the on-time may be 10 percent with the off-time at 90 percent. At low speeds, the on-time may be 90 percent and the off-time 10 percent.

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.

When the engine is running, the generator turn-on signal is sent to the generator from the PCM, turning on the regulator. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the 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 generator F terminal is connected internally to the voltage regulator and externally to the PCM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the PCM that a problem exists. The PCM monitors the generator field duty cycle signal circuit. The system voltage sense circuit receives B+ voltage that is Hot At All Times through the DIM fuse in the rear fuse block. This voltage is used by the regulator as the reference for system voltage control.

BATTERY SAVER ACTIVE -- 29

The DIC displays the BATTERY SAVER ACTIVE -- 29 message when the dash integration module (DIM) detects that the battery is in a heavy discharge condition for a long period of time. The blower fans, rear defogger, heated seats, and heated mirrors are disabled. The DIC receives a class 2 message from the DIM requesting illumination. The IPC sends a class 2 message to the radio in order to activate an audible warning.

Charging System Indicator

The IPC illuminates the charging system indicator when any of the following occur:

CHECK CHARGE SYSTEM -- 4

The DIC displays the CHECK CHARGE SYSTEM -- 4 message when any of the following occur: