Grand Cherokee 4WD V8-5.2L VIN Y (1998)
Powertrain Control Module: Description and Operation
SYSTEM OPERATION
Power Control Module (PCM) Location
The Powertrain Control Module (PCM) is located in the engine compartment.
The ignition system is controlled by the PCM.
NOTE: Base ignition timing by rotation of distributor is not adjustable.
The PCM opens and closes the ignition coil ground circuit to operate the ignition coil. This is done to adjust ignition timing, both initial (base) and
advance, and for changing engine operating conditions.
The amount of electronic spark advance provided by the PCM is determined by five input factors: engine coolant temperature, engine rpm, intake
manifold temperature, manifold absolute pressure and throttle position.
The speed control electronic control circuitry is integrated into the Powertrain Control Module (PCM). The PCM is located in the engine
compartment. The PCM speed control functions are monitored by the On-Board Diagnostics (OBD). All OBD sensed systems are monitored by
the PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in electronic memory for certain
failures it detects. See On-Board Diagnostic Test. The PCM cannot be repaired and must be replaced if faulty.
TRANSMISSION CONTROL
The Powertrain Control Module (PCM) controls operation of the converter clutch, overdrive clutch, and governor pressure solenoid.
The control module determines transmission shift points based on input signals from the transmission thermistor, transmission output shaft speed
sensor, crankshaft position sensor, vehicle speed sensor, throttle position sensor, and battery temperature sensor.
