Grand Cherokee 2WD V6-3.7L (2008)
Oil Pressure Warning Lamp/Indicator: Description and Operation
Oil Pressure Indicator
Description
DESCRIPTION
An oil pressure indicator is found only in the instrument cluster of SRT8 vehicles. The oil pressure indicator is an additional function of the Electronic
Vehicle Information Center (EVIC) and is selected using the STEP button in the upper instrument panel switch pod while in the trip computer mode.
This indication appears within the reconfigurable dot matrix Organic Light Emitting Diode (OLED) display unit.
The oil pressure indicator consists of an International Control and Display Symbol icon for Engine Oil , a gauge bar, and an alpha/numeric display of the
current oil pressure in either KPA (kilopascals) or PSI (Pounds/Square Inch), as selected with the U.S./METRIC feature of the EVIC. The indicator
displays values from 0 to 750 kPa, or from 0 to 100 psi. The oil pressure indicator appears in place of the compass/trip computer information in the
dot matrix display.
The dot matrix OLED is soldered onto the cluster electronic circuit board, and is visible through a window with a smoked clear lens located on the lower
edge of the tachometer gauge dial face of the cluster overlay. The dark lens over the OLED prevents the indicator from being clearly visible when it is
not illuminated. The oil pressure indicator appears in the same white color and at the same lighting level as the compass/trip computer information when
it is illuminated by the instrument cluster electronic circuit board.
The oil pressure indicator is serviced as a unit with the OLED in the instrument cluster.
Operation
OPERATION
The oil pressure indicator gives an indication to the vehicle operator of the engine oil pressure. This indicator is controlled by the instrument cluster logic
circuit based upon cluster programming, an input from the upper instrument panel switch pod, and electronic messages received by the cluster from the
Powertrain Control Module (PCM) over the Controller Area Network (CAN) data bus.
The oil pressure indicator function of the reconfigurable dot matrix Organic Light Emitting Diode (OLED) display unit is completely controlled by the
instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the
fused ignition switch output (run-start) circuit. Therefore, the OLED oil pressure indication will always be OFF when the ignition switch is in any
position except ON or START. The instrument cluster will turn ON the oil pressure indicator for the following reasons:
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Oil Pressure Indicator Request - Each time the cluster is in the compass/trip computer mode and receives a request from the STEP button on
the steering wheel to step to the appropriate sequence of the trip computer display, the oil pressure indicator will be displayed showing the current
engine oil pressure value. The cluster receives electronic engine oil pressure messages from the PCM indicating the current pressure. The
indicator remains illuminated until the cluster receives another request from the STEP button, until the cluster arbitrator logic determines that
another display request has priority, or until the ignition switch is turned to the OFF position, whichever occurs first.
The PCM continually monitors the engine oil pressure sensor to determine the engine oil pressure. The PCM then sends the proper messages to the