Engine Oil Level Sensor and/or Switch Diagnosis. Buick GL7 (Export) 2000

For 1990-2009 cars

### Circuit Description

The oil level switch is a 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 instrument panel cluster (IPC). The IPC 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 IPC. The engine coolant temperature Test Condition is required to ensure enough time has passed since the engine was last stopped. The coolant temperature difference is to allow enough time for the engine oil to drain back into the oil pan.

### Message Test Conditions

• | DTC's P0117, P0118 or P0603 not set.

• | Engine speed is 0 RPM.

• | The ECT must be more than 15°C (59°F).

• | The ECT at key ON must be at least 12°C (22°F) less than the ECT at the last key OFF.

### Diagnostic Aids

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

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

1. 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.

2. If the jumper fuse opens when connected, a short to voltage condition exists on the SIGNAL circuit. A short to voltage may damage the switch. Always check for proper switch operation after repairing a short to voltage.

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

1. Inspect that the engine oil level is within the proper operating range using the dipstick. Refer to Fluid and Lubricant Recommendations in Maintenance and Lubrication.

Fill or drain engine oil as required.

2. Turn the ignition ON while leaving the engine OFF.
3. Using the scan tool monitor the engine oil level display.

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. Observe the engine oil level display on the scan tool.

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

2500 RPM

System OK

Go to Step 7

4

1. Turn the ignition OFF.
2. Disconnect the engine oil level switch.
3. Turn the ignition ON while leaving the engine OFF.
4. Connect a fused jumper between the engine oil level switch terminals.
5. Observe the engine oil level display on the scan tool.

Does the display indicate engine oil level is OK?

--

Go to Step 10

Go to Step 5

5 | Connect the fused jumper between the engine oil level SIGNAL circuit terminal and a known good ground. Does the display indicate engine oil level is OK? | -- | Go to Step 9 | Go to Step 6

6

1. Turn the ignition OFF.
2. Remove the fused jumper.
3. Disconnect the PCM.
4. Test the engine oil level SIGNAL circuit for an open, high resistance or if the jumper fuse has blown, a short to voltage. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 2

Go to Step 12

7

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

Does the engine oil level display indicate LOW?

--

Go to Step 11

Go to Step 8

8

1. Turn the ignition OFF.
2. Disconnect the PCM.
3. Test the engine oil level SIGNAL circuit for a short to chassis ground or a short to the engine oil level switch ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 2

Go to Step 12

9

1. Turn the ignition OFF.
2. Disconnect the PCM.
3. Test the engine oil level GROUND circuit for an open or high resistance condition. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 2

Go to Step 12

10 | Inspect for proper terminal contact at the engine oil level switch connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 2 | Go to Step 11
11 | Replace the oil level switch. Did you complete the replacement? | -- | Go to Step 2 | --
12 | Inspect for proper terminal contact at the PCM connectors. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 2 | Go to Step 13
13 | Important: : Replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 2 | --