Low Engine Oil Level Indicator Always On

Low Engine Oil Level Indicator Always On

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle. Initial Inspection and Diagnostic Overview






Circuit/System Description

The engine oil level (EOL) sensor/switch is a normally closed switch that opens with a low engine oil level condition. With the ignition switch turned ON and the engine not running, the engine control module (ECM) or the powertrain control module (PCM) detects a low signal voltage at the signal circuit of engine oil level sensor/switch. When the engine is running and the engine oil level is low, the ECM/PCM detects a high signal voltage at the signal circuit of the engine oil level sensor/switch. The ECM/PCM monitors the engine oil level switch signal circuit. When the ECM/PCM detects a high signal voltage on the engine oil level switch signal circuit, the ECM/PCM sends a GMLAN serial data message to the instrument panel cluster (IPC) requesting the low engine oil indicator ON.

Diagnostic Aids

* When the Low Engine Oil Level indicator/message displays in the driver information center (DIC) due to a low engine oil level condition, make sure that the ignition is turned OFF before adding or changing the oil in the vehicle. Failure to do so may result in the Low Engine Oil Level indicator/message staying on after the engine attains proper oil level.
* When the Low Engine Oil Level indicator/message displays in the DIC and the ignition is not turned OFF before adding or changing the engine oil, the Low Engine Oil Level indicator/message may stay ON even after the proper oil level is attained. For the Low Engine Oil Level indicator/message to turn OFF, the engine has to undergo a thermocycle process, refer to Indicator/Warning Message Description and Operation
* Before replacing the IPC because of the Low Engine Oil Level indicator/message staying ON after an oil change or engine oil addition, it is necessary for the engine to undergo a thermocycle process. The IPC may not be malfunctioning but only needs the Low Engine Oil Level indicator/message to turn OFF after an engine thermocycle process. Refer to Indicator/Warning Message Description and Operation

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector of the engine oil level switch.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit and ground.

• If greater than 1.0 ohm, test the ground circuit for an open/high resistance.

3. Install a 3-amp fused jumper wire between the signal circuit and ground. Verify the scan tool Engine Oil Level Switch parameter is OK.

• If not OK, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

4. If all circuits test normal, test or replace the engine oil level switch.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification.

* Engine Oil Level Sensor and/or Switch Replacement for the 4.6L engine
* Engine Oil Level Sensor and/or Switch Replacement for the 3.8L engine
* Control Module References for the ECM/PCM replacement, setup and programming Verification Tests