GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Alero Export 🢒 Engine 🢒 Engine Controls - 3.4L 🢒 Engine Oil Pressure Sensor and/or Switch Diagnosis

Engine Oil Pressure Switch Diagnosis
Object Number: 328623 Size: SF
Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The PCM applies battery voltage through a pull up resistor to the Engine Oil Pressure Switch circuit. The PCM monitors the applied voltage on the Engine Oil Pressure Switch circuit. If the ignition switch is turned ON with the engine not running or engine oil pressure is below 35 kPa (5 psi), the Engine Oil Pressure switch grounds the PCM voltage input. The PCM sends the engine oil pressure information via Class II serial data to the Instrument Panel Cluster (IPC). The IPC controls the Engine Oil Pressure Indicator.

Diagnostic Aids

Check for the following condition(s):

    • Poor connections. Inspect PCM and harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
    • Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the Engine Oil Pressure switch, turn the ignition ON and observe a voltmeter connected between the Engine Oil Pressure switch connector terminals while moving wiring harnesses related to the Engine Oil Pressure Switch circuit. A change in voltage will indicate the location of the fault.

Engine Oil Pressure Switch Diagnosis

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Are any PCM DTCs stored?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

Is the Engine Oil pressure Indicator ON?

--

Go to Step 4

Go to Step 16

4

Check the engine for correct oil level.

Is the Correct engine oil level indicated?

--

Go to Step 5

Go to Step 11

5

Check the engine oil pressure with a manual pressure gauge.

Refer to Oil Pressure Diagnosis and Testing .

Is proper engine oil pressure indicated?

--

Go to Step 6

Go to Step 12

6
  1. Turn OFF the Ignition switch.
  2. Disconnect the engine oil pressure switch connector.
  3. Turn ON the ignition switch.
  4. Connect a test light to ground.
  5. Probe cavity A in the oil pressure switch connector.

--

Go to Step 7

Go to Step 9

7
  1. Connect the test light to B+.
  2. Probe cavity B in the oil pressure switch connector.

Is Test light on?

--

Go to Step 8

Go to Step 10

8
  1. Check for poor terminal connections in the oil pressure switch.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs .

Was a problem found?

--

Go to Step 16

Go to Step 13

9
  1. Check for the following circuit condition(s):
  2. Open or short to ground in the PCM feed to the engine oil pressure switch (CKT 231).
  3. Poor connections at the PCM.
  4. If a problem is found, repair as necessary. Refer to Wiring Repairs .

Was a problem found?

--

Go to Step 16

Go to Step 15

10

Locate and repair the following circuit condition(s):

  1. Open in the engine oil pressure ground.
  2. Poor terminal connections in the Underhood Electrical Center pass-through connector. Refer to Wiring Repairs .

Is action complete?

--

Go to Step 16

--

11

Determine cause of low oil.

Is action complete?

--

Go to Step 16

--

12

Determine cause of low oil pressure.

Is action complete?

--

Go to Step 16

--

13

Check the Communication circuit for correct operation.

Refer to Diagnostic System Check - Data Link Communications .

Was a problem Found?

--

Go to Step 16

Go to Step 14

14

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

Is action complete?

--

Go to Step 16

--

15

Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is action complete?

--

Go to Step 16

--

16

Check for the proper operation of Oil Pressure Indicator. Refer to Diagnostic System Check - Instrument Cluster .

Is the correct operation indicated?

--

System OK

Go to Step 2