MODEL IDENTIFICATION
Vehicle body codes are used throughout self-diagnostic tests. See BODY CODE DESIGNATION table for model identification.
| Model Name | Body Type |
|---|---|
| Cherokee | XJ |
| Grand Cherokee | WJ |
| Wrangler | TJ |
BODY CODE DESIGNATION
DESCRIPTION
Charging system consists of a Powertrain Control Module (PCM), generator, Malfunction Indicator Light (MIL) and battery. Generator consists of a rotor, stator, rectifiers, front and rear covers and drive pulley. Generator is serviced as a complete unit only. Voltage regulation is controlled by the Powertrain Control Module (PCM). Electronic Voltage Regulator (EVR) is not a separate component, but a circuit located within the PCM. If EVR circuit is defective, PCM must be replaced.
OPERATION
The amount of amperage produced by the generator is controlled by Electronic Voltage Regulator (EVR) circuitry within the PCM. EVR circuity is connected in series with the generator field driver terminal and ground. A Battery Temperature Sensor (BTS), located in battery tray, is used to sense battery temperature. Sensed battery temperature and data from monitored line voltage is used by PCM to adjust battery charging rate. This is accomplished by cycling the ground path to control the strength of generator rotor magnetic field. PCM then compensates and regulates generator amperage output accordingly.
The PCM monitors critical input to control fuel injection, ignition, emission and other engine management functions. The PCM is also programmed to monitor charging system related circuits
- Battery feed to PCM.
- Generator field control.
- Battery charging voltage (high and low).
If a problem is sensed in a monitored circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM memory and Malfunction Indicator Light (MIL) will illuminate, provided specific criteria have been met. DTCs can be read using MIL, Chrysler's Diagnostic Readout Box (DRB-III), or a generic scan tool.
Note. DTC is erased from memory if failure does not reoccur after 50 engine starts.
Certain DTCs cause MIL to illuminate and PCM to enter limp-in mode. In limp-in mode, PCM attempts to compensate for particular component failure by substituting information from other sources. This allows vehicle operation until proper repairs are made.