Grand Cherokee 2WD L6-4.0L VIN S (1997)
Oil Pressure Gauge: Description and Operation
System Operation
SYSTEM OPERATION
The oil pressure gauge gives an indication of the engine oil pressure. The instrument cluster circuitry controls the gauge pointer position. The
instrument cluster circuitry calculates the proper gauge pointer position based upon an engine oil pressure message received from the Powertrain
Control Module (PCM) on the Chrysler Collision Detection (CCD) data bus.
The PCM uses an input from the engine oil pressure sensor and internal programming to decide what engine oil pressure message is required. The
PCM then sends the proper message to the instrument cluster and the Body Control Module (BCM) on the CCD data bus.
The BCM monitors the PCM engine oil pressure messages. If the PCM message indicates that engine oil pressure is too low, the BCM sends a
message to the instrument cluster to turn on the Check Gauges lamp and to drive the oil pressure gauge needle to the zero end of the gauge scale.
The engine oil pressure sensor is installed in a threaded hole that penetrates an oil passage of the engine. The engine oil pressure sensor contains a
flexible diaphragm and a variable resistor coil. The diaphragm moves in response to changes in the engine oil pressure, which changes the internal
electrical resistance of the sensor.
