GM Service Manual Online
For 1990-2009 cars only

Object Number: 383968  Size: SF
Engine Controls Component Views
Miscellaneous
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The engine oil pressure (EOP) sensor is mounted at the top rear of the engine. The EOP sensor measures changes in engine oil pressure. The EOP sensor has a 5 volt reference, a ground and a signal circuit.

The Engine Oil Pressure sensor changes resistance based on changes in engine oil pressure. When the PCM senses a signal voltage lower than the normal operating range of the sensor, this DTC sets.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The EOP sensor voltage is less than 0.48 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 (DIC) displays a message.
    • The EOP gauge displays 0 psi.

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 connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the module. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM.
   • For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616 . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.

    • The PCM 5.0 volt reference circuits are internally connected within the PCM. If all the Engine Oil sensor circuits are OK, inspect related 5.0 volt reference circuits. Refer to DTC P1635 5 Volt Reference 1 Circuit .
    • Using 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 aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.) that you observed. This isolates when the DTC failed.
    • For an intermittent, refer to Symptoms .

Test Description

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

  1. This step determines if the malfunction is present.

  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. If the scan tool displays 5.0 volts, this indicates that the Engine Oil Pressure sensor signal, 5.0 volt reference circuit and PCM are OK.

  4. If the scan tool displays 5.0 volts, this indicates that the Engine Oil Pressure sensor signal circuit and PCM are OK.

  5. Disconnecting the PCM allows using the DMM to test the continuity of the circuits. This aids in locating an open or shorted circuit.

Step

Action

Values

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

Important: Before proceeding with the Engine Oil Pressure sensor diagnostic, perform the engine oil pressure test. Refer to Oil Pressure Diagnosis and Testing in Engine Mechanical-5.7L.

  1. Install the scan tool.
  2. Start the engine.
  3. Monitor the DTC Information 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. Turn ON the ignition leaving the engine OFF.
  2. Monitor the Engine Oil Pressure voltage using the scan tool.

Is the Engine Oil Pressure voltage below the specified value?

0.48V

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 observe the parameters.
  3. Turn OFF the ignition for 15 seconds.
  4. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in the Freeze Frame/Failure Records as possible. Special operating conditions that you need to meet 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. Disconnect the Engine Oil Pressure sensor electrical connector. Refer to Engine Oil Pressure Sensor or Switch Replacement in Instrument Panel, Gauges and Console.
  2. Jumper the 5 volt reference circuit and the Engine Oil Pressure signal circuit together at the Engine Oil Pressure sensor harness connector.
  3. Observe the Engine Oil Pressure voltage display on the scan tool.

Is the Engine Oil Pressure voltage near the specified value?

5V

Go to Step 11

Go to Step 6

6

  1. Connect the test lamp J 35616-200 between B+ and the Engine Oil Pressure sensor signal circuit at the Engine Oil Pressure sensor harness connector.
  2. Observe the Engine Oil Pressure voltage display on the scan tool.

Is the Engine Oil Pressure voltage at the specified value?

5V

Go to Step 7

Go to Step 9

7

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C1 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement .
  3. Test the 5 volt reference circuit for an open or short to ground.
  4. Repair the 5 volt reference circuit if it is open or shorted to ground. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 8

8

  1. Inspect the 5 volt reference circuit for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. Replace the terminal if necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

9

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C2 located on the opposite side of the manufacturer's logo. Refer to Powertrain Control Module Replacement .
  3. Test the Engine Oil Pressure signal circuit for the following:
  4. • Open circuit
    • Short to ground
    • Short to sensor ground circuit
  5. Repair the Engine Oil Pressure sensor signal circuit if it is open or shorted to ground. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

10

  1. Inspect the Engine Oil Pressure sensor signal circuit for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find a poor connection, replace the terminal. Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

11

Important: Before replacing the sensor inspect for poor connections.

Replace the Engine Oil Pressure sensor. Refer to Engine Oil Pressure Sensor or Switch Replacement in Instrument Panel, Gauges and Console.

Is the action complete?

--

Go to Step 13

--

12

Important: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement .

Is the action complete?

--

Go to Step 13

--

13

  1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option using the scan tool.
  2. Start the engine and idle 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 14

Go to Step 2

14

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