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 powertrain control module (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 Class II message to the Instrument Panel (IP) Cluster. The IP Cluster 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 IP Cluster. The engine coolant temperature Test Condition is required to ensure enough time has passed since the engine was last stopped. The time period/coolant temperature difference is to allow enough time for the engine oil to drain 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.

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.

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

1. Ensures that the Powertrain On Board Diagnostic (OBD) System Check is performed before proceeding with this diagnosis. Go to any DTCs that are set first.