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 . Testing and Inspection
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 displays in the IPC or 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 or message staying on after the engine attains proper oil level.
- When the Low Engine Oil Level indicator displays in the IPC or DIC and the ignition is not turned OFF before adding or changing the engine oil, the Low Engine Oil Level indicator may stay ON even after the proper oil level is attained. For the Low Engine Oil Level indicator 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 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 to turn OFF after an engine thermocycle process. Refer to Indicator/Warning Message Description and Operation
CIRCUIT/SYSTEM TESTING
1. With the ignition ON and the scan tool installed, observe the Low Engine Oil Level Indicator display in the IPC and the scan tool Low Engine Oil Level Indicator Command parameter in the ECM/PCM IPC Data List.
- If the Low Engine Oil Level Indicator does not display in the IPC and the scan tool Low Engine Oil Level Indicator Command parameter displays OFF, check for a poor connection at the harness connector of the engine oil level switch.
2. With the scan tool installed, observe the Engine Oil Level Switch parameter in the ECM/PCM Engine Data List.
- If the Engine Oil Level Switch parameter displays OK, replace the IPC.
3. With the ignition OFF, disconnect the engine oil level switch.
4. Connect a 3-amp fused jumper wire between the engine oil level switch signal circuit and a good ground.
5. With the ignition ON, and the scan tool installed, observe the Engine Oil Level Switch parameter in the ECM/PCM Engine Data List.
- If the Engine Oil Level Switch parameter displays OK, check the engine oil level switch ground circuit for an open or a high resistance.
- If the engine oil level switch ground circuit tests normal, replace the engine oil level switch.
- If the Engine Oil Level Switch parameter displays Low, check the engine oil level signal circuit for an open, a high resistance or a short to voltage.
- If the engine oil level switch signal circuit tests normal, replace the ECM/PCM
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