Oil Level Sensor: Description and Operation

DESCRIPTION
The oil level is determined by an optical sensor which detects oil level immediately upon power-up. While the engine oil level sensor is determining oil level, the sensor holds the state of the engine oil level signal at ignition voltage. The amount of time the engine oil level sensor requires to determine oil level is about 1.5 seconds. After the engine oil level has been determined, the engine oil level sensor will ground the engine oil level signal for 1 to 2 seconds if oil level is OK or 6 to 10 seconds if oil level is low. The PCM determines oil level based on the engine oil level signal duration. The PCM also monitors the engine oil level signal to determine whether the engine oil level PCM input circuit is open or shorted.

The Low Oil Level Lamp will be illuminated for about a minute after the ignition has been turned ON when the PCM tests for low oil level and the engine oil level sensor indicates that a low oil level condition exists. The PCM determines whether or not to test for low oil level based on the difference between engine coolant temperature at the last shutdown and engine coolant temperature at start-up. This is to ensure that the oil has drained back into the sump before testing. When the ignition is first turned ON, the PCM commands the Low Oil Level lamp ON for a brief period of time to test the bulb.