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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Corvette 🢒 DTC 🢒 DTC P0523 Engine Oil Pressure (EOP) Sensor Circuit High Voltage

Object Number: 71097 Size: SF
OBD II Symbol Description Notice
Engine Controls Components
Cell 20: Miscellaneous
Handling ESD Sensitive Parts Notice

Circuit Description

The Engine Oil Pressure sensor is mounted in the top rear of the engine. The Engine Oil Pressure sensor measures changes in engine oil pressure. The Engine Oil Pressure sensor has a 5.0 volt reference, a ground and a signal circuit.

The Engine Oil Pressure sensor changes resistance based on pressure.

When the PCM senses a signal voltage higher than the normal operating range of the sensor, this DTC will set.

Conditions for Running the DTC

Engine running.

Conditions for Setting the DTC

Engine Oil Pressure sensor is greater than 4.5 volts.

Action Taken When the DTC Sets
    • The PCM stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
    • The driver information center displays a message.

Conditions for Clearing the DTC
    • A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
    • A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • Use a scan tool in order to clear the DTC.

Diagnostic Aids:

Important: Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM\TAC modules.

    • The following may cause an intermittent:
       - Mis-routed harness.
       - Rubbed through wire insulation.
       - Broken wire inside the insulation.
    • The PCM 5.0 volt reference circuits are internally connected within the PCM. If all the Engine Oil Pressure sensor circuits check to be OK, inspect related 5.0 volt reference circuits. Refer to DTC P1635.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if the malfunction is present. For any test that requires probing of the PCM or any component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit prevents damage to the harness connector terminals.

  2. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.

    3.

  3. This step checks if the signal circuit is shorted to a voltage.

    4.

  4. This step checks if a ground circuit is available at the Engine Oil Pressure sensor.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Install the scan tool.
  2. Idle the engine.
  3. Monitor the Failed This Ignition under DTC Status for DTC P1635 using the scan tool.

Did DTC P1635 fail this ignition cycle?

--

Go to DTC P1635 5 Volt Reference 1 Circuit

Go to Step 3

3

  1. Install the scan tool.
  2. Idle the engine.
  3. Monitor the Engine Oil Pressure sensor voltage on the scan tool.

Is the Engine Oil Pressure sensor voltage above the specified value?

4.5V

Go to Step 5

Go to Step 4

4

  1. Turn ON the ignition leaving the engine OFF.
  2. Review the Freeze Frame and/or Failure Records data for this DTC and note parameters.
  3. Turn OFF the ignition for 15 seconds.
  4. Start the engine and operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame/Failure Records as possible. Special operating conditions that need to be met before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
  5. Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, and enter the DTC number using the scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 5

Go to Diagnostic Aids

5

  1. Remove the intake manifold. Refer to Engine Mechanical.
  2. Disconnect the Engine Oil Pressure sensor electrical connector.
  3. Observe the Engine Oil Pressure sensor voltage displayed on the scan tool.

Is the Engine Oil Pressure sensor voltage below the specified value?

1.0V

Go to Step 6

Go to Step 7

6

Probe the sensor ground circuit with a test lamp J 35616-200 to B+.

Is the test lamp illuminated?

--

Go to Step 8

Go to Step 9

7
  1. Check the Engine Oil Pressure signal circuit for a short to voltage or a short to the 5.0 volt reference circuit.
  2. Repair the Engine Oil Pressure sensor signal circuit if it is shorted. Refer to Body and Accessories/Wiring Systems.

Was the Engine Oil Pressure sensor signal circuit shorted?

--

Go to Step 14

Go to Step 11

8

Measure the voltage at the 5.0 volt reference circuit to ground using a DMM J 39200 .

Is the voltage greater than the specified value?

5.0V

Go to Step 13

Go to Step 9

9
  1. Check for a poor sensor ground terminal connection at the PCM connector.
  2. If you find a problem, replace the faulty terminal. Refer to Body and Accessories/Wiring Systems.

Did the terminal require replacement?

--

Go to Step 14

Go to Step 10

10
  1. Check the continuity of the Engine Oil Pressure sensor ground circuit.
  2. If you find that the Engine Oil Pressure sensor ground circuit measures over the specified value, repair the open or the poor connection. Refer to Body and Accessories/Wiring Systems.

Was a condition found and corrected?

5 ohms

Go to Step 14

Go to Step 11

11

Important:: Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .

Replace the PCM.

Is the action complete?

--

Go to Step 14

--

12

Important:: Before replacing the Engine Oil Pressure sensor perform the engine oil pressure check. Refer to Engine Mechanical.

Replace the Engine Oil Pressure sensor. Refer to Engine Oil Pressure Sensor and/or Switch Replacement .

Is the action complete?

--

Go to Step 14

--

13

Repair the 5.0 volt reference circuit for a short to voltage.

Is the action complete?

--

Go to Step 14

--

14
  1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option using the scan tool.
  2. Idle the engine at the normal operating temperature.
  3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
  4. Operate vehicle within the Conditions for Running this DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 15

Go to Step 2

15

Select the Capture Info option and the Review Info option using the scan tool.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to the applicable DTC table

System OK