Circuit Description
The oil level switch is a normally open switch. When the oil level is within an acceptable range the oil level switch closes. The switch opens when the engine oil level drops below a predetermined amount. The powertrain control module (PCM) tests the engine oil level switch circuit with the ignition ON, engine OFF. The PCM monitors the engine coolant temperature to ensure proper engine oil drain back to the oil pan. When the engine is colder the engine oil drain back process takes a greater amount of time.
The PCM sends a message via Class 2 to the instrument panel cluster (IPC) to turn ON the oil level message when the engine oil level drops below a predetermined value and the conditions for running the test are met.
Conditions for Testing for Low Engine Oil
| • | DTC P0117 and P0118 are not set. |
| • | The ignition is ON with the engine OFF. |
| • | The PCM compares the last ignition OFF engine coolant temperature, stored temperature, to the ignition ON engine coolant temperature. |
| • | If the PCM determines the ignition ON engine coolant temperature is cooler then ignition OFF engine coolant temperature by a predetermined amount, the PCM tests the engine oil level sensor circuit. The following table illustrates the required temperatures to enable the engine oil level test: |
Low Engine Oil Level Coolant Temperature Enable Conditions | ||
|---|---|---|
Ignition ON Temperature | Minimum Stored Temperature to Run Test | Temperature Difference |
-40°C (-40°F) | -15°C (5°F) | 25°C (45°F) |
-28°C (-18°F) | -15°C (5°F) | 13°C (23°F) |
-16°C to 140°C (3°F to 284°F) | -6°C to 130°C (21°F to 266°F) | 10°C (18°F) |
Conditions for Clearing the Low Engine Oil Level Message
| • | Repair the engine low oil level circuit or low oil level condition as necessary. |
| • | Start and idle the engine. |
| • | Allow the engine to reach operating temperature of 90°C (194°F). |
| • | Turn OFF the engine. |
| • | The ignition must remain OFF for a minimum of one hour. The engine coolant temperature should decrease by 10°C (-18°F). When you turn the ignition ON the conditions for performing the test should be met and the Low Engine Oil message clears. |
Diagnostic Aids
Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
The following may cause an intermittent:
| • | Poor connections -- Check for adequate terminal tension. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. |
| • | Corrosion |
| • | Mis-routed harness |
| • | Rubbed through wire insulation |
| • | Broken wire inside the insulation |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This steps tests the Oil Level sensor signal circuit between the PCM and the sensor.
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This steps tests the Oil Level sensor ground circuit between the PCM and the sensor.
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This steps tests for an open in the Oil Level sensor signal circuit between the PCM and the Oil Level sensor.
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This steps tests the Oil Level signal circuit for a short to ground.
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This steps Clears the Low Oil Level message. The engine coolant temperature should decrease by 10°C (18°F). When you turn ON the ignition the conditions for performing the test should be met and the Low Engine Oil message clears.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Is the oil level within range? | -- | ||
3 |
Does the scan tool display Low Oil Level as YES? | -- | ||
4 | Is the customer concern that the engine oil level was low and the Low Oil Level message never illuminated? | -- | ||
5 | Is the customer concern that the oil was just added or that an oil change was just done and the Low Oil Level message did not clear? | -- | Go to Diagnostic Aids | |
Is the voltage at the specified value? | B+ | |||
Measure the voltage from the signal circuit to the ground circuit at the engine oil level sensor electrical connector using the DMM . Refer to Measuring Voltage in Wiring Systems. Is the voltage at the specified value? | B+ | |||
Does the DMM indicate continuity? | -- | |||
Probe the engine oil level sensor signal circuit using the Test Lamp connected to B+. Does the test lamp illuminate? | -- | |||
10 |
Did you find and correct the condition? | -- | ||
11 | Repair the open ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
12 | Repair the open signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
13 | Repair the short to ground in the signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
14 |
Did you find and correct the condition? | -- | ||
15 |
Important:: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | -- | |
16 | Replace the engine oil level sensor. Is the action complete? | -- | -- | |
17 | Add the appropriate amount of oil. Is the action complete? | -- | -- | |
Important: The ignition must remain OFF for a minimum of one hour. Is the action complete? | 90°C (194°F) | System OK | -- |
