GM Service Manual Online
For 1990-2009 cars only

Object Number: 155150  Size: SF
Engine Controls Components
Cell 20: Generator, Power Steering Press Switch and Oil Level Switch
OBD II Symbol Description Notice
ESD Notice

Circuit Description

The oil level switch is a magnetic reed float style switch which is closed with oil level full and open when oil level is low. The PCM monitors the oil level switch to determine if the oil is LOW or OK. When the Test Conditions have been met the PCM will monitor the oil level switch input. If a low oil level is indicated the PCM will send a serial data message to the Driver Information center (DIC). The DIC will then indicate the oil level is low. If the Test Conditions have not been met then the PCM ignores the oil level switch input and oil level OK is indicated to the DIC. The engine coolant temperature Test Condition is used to ensure that the engine has been OFF long enough to ensure the engine oil has drained back into the oil pan. The colder the current engine temperature is, the larger the drop in temperature necessary. This is to ensure colder, thicker oil has drained back into the oil pan.

Test Conditions

    • DTCs P0117, P0118 or P0603 not set.
    • Engine speed is 0 RPM.
    • The current engine coolant temperature is from 5°C to 20°C less than the temperature stored when the engine was last running.

Important: The oil level switch is mounted to the oil pan at a level below the full level. Removal of the switch may drain several quarts of oil.

Test Description

  1. The Powertrain OBD System Check must be performed before proceeding with this diagnosis. Go to any DTC's that are set first.

  2. With the engine speed at or above 2300 RPM the engine oil switch should indicate LOW oil level. The engine oil is scavenged to a level that is below the switch during higher engine speed and also during some lateral vehicle movement conditions.

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

  1. Check the oil level of the engine is within the proper operating range using the oil dipstick.
  2. Fill or drain the engine oil if required.

  3. Using the scan tool monitor the engine oil level display with the ignition ON and the engine OFF.

Does the display indicate the oil level is OK?

--

Go to Step 3

Go to Step 4

3

  1. Start and idle the engine.
  2. Raise the engine speed to the specified value.
  3. Monitor the engine oil level display.

Does the engine oil level display indicate LOW while engine speed is at the specified value?

2300 RPM

Fault not present. Go to Diagnostic Aids

Go to Step 7

4

  1. Disconnect the engine oil level switch.
  2. Connect a fused jumper between the engine oil level switch terminals A and B.

Does the engine oil level display indicate the oil level is OK?

--

Go to Step 12

Go to Step 5

5

Place the jumper between terminal A and a known good engine ground.

Does the display indicate the engine oil is OK ?

--

Go to Step 10

Go to Step 6

6

  1. Turn the ignition OFF.
  2. Remove the fused jumper.
  3. Disconnect PCM connector C2.
  4. Using the DMM measure the resistance of the engine oil level switch input circuit between the switch terminal A and the PCM connector C2.

Is the resistance the same or less than the value specified?

5 ohms

Go to Step 14

Go to Step 9

7

  1. Turn the ignition ON and the engine OFF.
  2. Disconnect the engine oil level switch connector.

Does the engine oil level display indicate the oil level is LOW?

--

Go to Step 12

Go to Step 8

8

  1. Turn the ignition OFF.
  2. Disconnect PCM connector C2.
  3. Using the DMM measure the resistance of the engine oil level switch input circuit between the switch terminal A and a known good engine ground.

Is the resistance the same or more than the value specified?

10K ohms

Go to Step 14

Go to Step 11

9

Repair the open in the engine oil level input circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis

--

10

Repair the open in the engine oil level switch ground circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis

--

11

Repair the short to ground in the engine oil level switch input circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis

--

12

  1. Check the terminal contact at the engine oil level switch connector.
  2. Repair terminal contact if needed.

Was the terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis

Go to Step 13

13

Replace the engine oil level switch.

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis

--

14

  1. Check terminal contact at the PCM.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis

Go to Step 15

15

Replace the Powertrain Control Module. Refer to Powertrain Control Module Replacement .

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis

--