For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category

### DTC Descriptor

DTC P250A: Engine Oil Level Sensor Circuit

### Circuit/System Description

The engine oil level (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 GMLAN serial data message.

### Conditions for Running the DTC

The engine is running.

### Conditions for Setting the DTC

• | The ECM detects that the EOP sensor signal circuit is greater than 4.4 volts.

• | The above condition is present for greater than 10 seconds.

### Action Taken when the DTC Sets

DTC P250A is a type C store Only DTC.

### Conditions for Clearing the MIL/DTC

DTC P250A is a type C store Only DTC.

### Reference Information

#### Schematic Reference

• | Instrument Cluster Schematics

• | Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) sensor.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit and a known ground.

⇒ | If greater than 1 ohm, 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 5 volt reference circuit and a known ground.

⇒ | If less than 4.8 volts, test the 5 volt reference circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the ECM.

⇒ | If greater than 5.2 volts, test the 5 volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Connect an approved test lamp between the 5-volt reference circuit and the signal circuit at the wiring harness connector.

⇒ | If the test lamp does not illuminate test the signal circuit for a open/high resistance. If the circuit tests normal replace the ECM.

5. If all circuits test normal, test or replace the EOP sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Engine Oil Pressure Sensor and/or Switch Replacement.

• | Engine Control Module Replacement for engine control module replacement, setup and programming.