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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1997 🢒 Corvette 🢒 DTC 🢒 DTC P1187 Engine Oil Pressure (EOP) Sensor Circuit Low 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 engine oil pressure.

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

Conditions for Setting the DTC
    • Engine running.
    • Engine Oil Pressure 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 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:
    • 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 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. 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.

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

    5.

  5. Disconnecting the PCM allows using the DMM J 39200 to check the continuity of the circuits. This aids in locating an open or shorted circuit.

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

Idle the engine and monitor the Engine Oil Pressure voltage using the scan tool.

Is the Engine Oil Pressure voltage below the specified value?

0.48 V

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 Setting 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.
  2. Jumper the 5.0 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?

5.0 V

Go to Step 11

Go to Step 6

6

  1. Connect a 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?

5.0 V

Go to Step 7

Go to Step 9

7

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector located on the opposite side of the manufacturer's logo.
  3. Check the 5.0 volt reference circuit for an open or short to ground. Refer to Body and Accessories/Wiring Systems.
  4. Repair the 5.0 volt reference circuit if it is open or shorted to ground.

Was the 5.0 volt reference circuit open or shorted to ground?

--

Go to Step 13

Go to Step 8

8
  1. Check the 5.0 volt reference circuit for a poor connection at the PCM.
  2. Replace the terminal if necessary. Refer to Body and Accessories/Wiring Systems.

Did the terminal require replacement?

--

Go to Step 13

Go to Step 12

9
  1. Turn OFF the ignition.
  2. Disconnect the PCM connector located on the opposite side of the manufacturer's logo.
  3. Check the Engine Oil Pressure signal circuit for the following:
    4. • Open circuit
    • Short to ground
    • Short to sensor ground circuit
  4. Repair the Engine Oil Pressure sensor signal circuit if it is open or shorted to ground. Refer to Body and Accessories/Wiring Systems.

Was the Engine Oil Pressure signal circuit open or shorted to ground?

--

Go to Step 13

Go to Step 10

10
  1. Check the Engine Oil Pressure sensor signal circuit for a poor connection at the PCM.
  2. If you find a poor connection, replace the terminal. Refer to Body and Accessories/Wiring Systems.

Did the terminal require replacement?

--

Go to Step 13

Go to Step 12

11

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

Replace the Engine Oil Pressure sensor. Refer to Engine Oil Pressure Sensor Replacement .

Is the action complete?

--

Go to Step 13

--

12

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 13

--

13
  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 setting 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