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 prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
The engine oil level (EOL) 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) 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 detects a high signal voltage at the signal circuit of the engine oil level sensor/switch. The ECM monitors the engine oil level switch signal circuit. When the ECM detects a high signal voltage on the engine oil level switch signal circuit, the ECM 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.
- 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 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 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 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

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Engine Oil Level Sensor and/or Switch Replacement
- Control Module References for the IPC or ECM/PCM replacement, setup and programming