Engine Oil Pressure Indicator Always On
Engine Oil Pressure Indicator Always On
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides 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) supplies 5-volts to the EOP sensor via the 5-volt reference circuit and provides ground via the EOP low reference circuit. The ECM 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 senses a high signal voltage. When the engine oil pressure is low, the EOP sensor voltage is low and the ECM senses a low signal voltage. The ECM sends the EOP information to the instrument panel cluster (IPC) via serial data message. The IPC illuminates the engine oil pressure indicator when it receives a serial data message indicating a low engine oil pressure condition.
Reference Information
Schematic Reference
Instrument Cluster Schematics (Instrument Cluster Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
* Indicator/Warning Message Description and Operation (Indicator/Warning Message Description and Operation)
* Instrument Cluster Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning)
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the EOP sensor.
2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal A and ground.
• If greater than the specified value, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, test for 4.8-5.2 volts between the appropriate 5-volt reference circuit and ground.
* 5-volt reference circuit terminal B (LY7 - Gas, 6 Cylinder, 3.6L, SFI, V6)
* 5-volt reference circuit terminal C (LH2 - Gas, 8 Cylinder, 4.6L, SFI, V8, DOHC, HO)
• If less than the specified value, test the appropriate 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
• If greater than the specified value, test the appropriate 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Verify the scan tool Engine Oil Pressure Sensor parameter is greater than 880 kPa (127.6 psi).
• If less than the specified value, test the appropriate signal circuit for a short to ground.
* Engine oil pressure switch signal circuit terminal C (LY7 - Gas, 6 Cylinder, 3.6L, SFI, V6)
* Engine oil pressure switch signal circuit terminal B (LH2 - Gas, 8 Cylinder, 4.6L, SFI, V8, DOHC, HO)
If the circuit tests normal replace the ECM.
5. Install a 3-amp fused jumper between the signal circuit and the low reference circuit. Verify the scan tool Engine Oil Pressure Sensor parameter is less than 8 kPa (1.16 psi).
• If greater than specified value, test the appropriate signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
6. Ignition ON, with the scan tool command the indicators OFF.
• If the EOP indicator does not turn OFF, replace the IPC.
7. If all circuits test normal, replace the EOP sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Engine Oil Pressure Sensor and/or Switch Replacement (Service and Repair) for the 4.6L engine
* Engine Oil Pressure Sensor and/or Switch Replacement (Service and Repair) for the 3.6L engine
* Control Module References (Programming and Relearning) for the IPC or ECM replacement, setup and programming