The engine oil pressure switch is a normally closed switch that opens with the proper oil pressure. With the ignition switch turned ON and the engine not running, the engine control module (ECM) should detect a low signal voltage input. With the engine running, the engine oil pressure switch opens and the ECM should detect a high signal voltage input. When the oil pressure is low, the ECM sends a message via High Speed CAN-Bus to the body control module (BCM). The BCM then sends a message via Low Speed CAN-Bus to the instrument cluster requesting the engine oil pressure indicator turned ON.

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Indicator/Warning Message Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

With LLU

Ignition ON, observe the scan tool ECM - Engine Oil Pressure Switch parameter with the ignition switch turned ON and the engine not running the reading should be Low with the engine running the reading should be OK.

Except LLU

1. Ignition ON, command the All Indicators test ON and OFF with the scan tool, verify that the engine oil pressure indicator changes between turn ON and OFF.

⇒	If the engine oil pressure indicator always stays on or always off, replace the P16 Instrument Cluster.

2. If the engine oil pressure indicator changes between ON and OFF, replace the K20 Engine Control Module (ECM).

With LLU

1. Ignition OFF, disconnect the harness connector at the B37 Engine Oil Pressure Switch.
2. Ignition ON, verify the scan tool ECM - Engine Oil Pressure Switch parameter is OK.

⇒	If not the specified value, test for the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

3. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool ECM - Engine Oil Pressure Switch is Low.

⇒	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Command the P16 Instrument Cluster All Indicators output function ON and OFF with the scan tool. The engine oil pressure indicator should turn ON and OFF when changing between the commanded states.

⇒	If the engine oil pressure indicator always on or always off, replace the P16 Instrument Cluster

5. If all circuits test normal, test or replace the B37 Engine Oil Pressure Switch.

Static Test

1. Ignition OFF, disconnect the harness connector at the B37 Engine Oil Pressure Switch.
2. Test for infinite resistance between the signal terminal listed below and ground with the switch in the open position.

•	Terminal 1 except LDK

•	Terminal A with LDK

⇒	If not the specified value, replace the B37 Engine Oil Pressure Switch.

3. Test for less than 5 Ω between the signal terminal listed below and ground with the switch in the closed position.

•	Terminal 1 except LDK

•	Terminal A with LDK

⇒	If greater than the specified range, replace the B37 Engine Oil Pressure Switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.