Engine Oil Pressure Indicator Always On
Engine Oil Pressure Indicator Always On (3.9L Engine)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provide an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The engine oil pressure (EOP) sensor changes voltage based on the engine oil pressure. The EOP sensor is a 3-wire sensor comprising of the signal circuit, the low reference circuit, and the 5-volt reference circuit. The engine control module (ECM) or the powertrain control module (PCM) supplies 5 volts to the EOP sensor via the 5-volt reference circuit and provides ground via the EOP low reference circuit. The ECM/PCM monitors the signal circuit of the EOP sensor to determine the engine oil pressure sensor voltage is within the normal operating range of approximately 1-4 volts. When the engine oil pressure is high, the EOP sensor voltage is high and the ECM/PCM senses a high signal voltage. When the engine oil pressure is low, the EOP sensor voltage is low and the ECM/PCM senses a low signal voltage. The ECM/PCM sends the EOP information to the instrument panel cluster (IPC) via GMLAN serial data message. The IPC illuminates the engine oil pressure indicator when it receives a GMLAN serial data message indicating a low engine oil pressure condition.
Circuit/System Testing
Ignition ON, scan tool installed, perform the Displays Test in the IPC Output Controls Special Functions. Verify that the engine oil pressure (EOP) indicator turns OFF after the Displays Test.
If the EOP indicator does not turn OFF after the Displays Test, test or replace the IPC.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Fuel Level Sensor Replacement
* Refer to Programming and Relearning. Programming and Relearning