GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The powertrain control module (PCM) or the engine control module (ECM) monitors the signal circuit of the engine oil pressure (EOP) sensor. When the oil pressure is high, the sensor is open, and the PCM/ECM senses a high signal voltage. When the oil pressure is low, the sensor is closed, and the PCM/ECM senses a low signal voltage.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0520 Engine Oil Pressure (EOP) Sensor Circuit

Conditions for Running the DTC

The ignition is ON, with the engine ON.

Conditions for Setting the DTC

    • The PCM/ECM detects that the EOP sensor signal circuit is pulled low.
    • The above condition is present for greater than 5 seconds.

Action Taken When the DTC Sets

    • The PCM/ECM records the operating conditions at the time the diagnostic test fails. The PCM/ECM displays this information in the Failure Records on the scan tool.
    • The instrument panel cluster (IPC) illuminates the engine oil pressure indicator.

Conditions for Clearing the DTC

    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction-free warm-up cycles.
    • The PCM/ECM receives a clear code command from the scan tool.

Diagnostic Aids

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

Refer to Testing for Intermittent Conditions and Poor Connections .

Step

Action

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Disconnect the engine oil pressure switch.
  2. Connect a test lamp from battery positive voltage to the engine oil pressure (EOP) switch terminal.
  3. Start the engine.
  4. Observe the test light.

Does the test light illuminate?

Go to Step 4

Go to Step 3

3

Test the signal circuit of the oil pressure switch for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 9

Go to Step 5

4

Inspect for poor connections at the harness connector of the EOP switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 9

Go to Step 6

5

Inspect for poor connections at the harness connector of the powertrain control module (PCM)/engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 9

Go to Step 7

6

Replace the EOP switch. Refer to the following:

    •  Engine Oil Pressure Sensor and/or Switch Replacement for the 3.5L (LX9) engine

Did you complete the replacement?

Go to Step 9

--

7

Replace the PCM or the ECM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 9

--

8

Replace the instrument panel cluster (IPC). Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 9

--

9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2