Oil Level Warning Indicator: Description and Operation

LOW OIL INDICATOR LAMP

The PCM commands the Low Oil Level Lamp ON if 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 startup. This is to ensure that the oil has drained back into the oil pan before testing.

The engine oil level switch is a simple float switch that is grounded when the engine oil level is OK. 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 (approximately 3 seconds). The PCM also checks the engine oil level switch circuit at startup. If the engine has been running, the PCM performs a test routine based on engine coolant temperature to ensure that the engine oil drained back into the sump before checking the state of the engine oil level switch. If the engine coolant temperature is between 15°C (59°F) and 130°C (266°F), the PCM compares the engine coolant temperature at the last key OFF to the engine coolant temperature at the current key ON. If the difference between the recorded temperature values is at least 12°C (54°F), the PCM will test the engine oil level.

The low oil indicator is controlled by either of the following components:
^ The powertrain control module (PCM)
^ The instrument cluster

The PCM receives oil level information from the engine oil level switch. When a low engine oil condition exists, the PCM sends a Class 2 message through circuit 1036 to the instrument cluster in order to turn on the low oil indicator.

The instrument cluster turns the low oil indicator on for approximately 3 Seconds at bulb test.

The LOW OIL indicator ground is controlled by the engine oil level indicator control module. In order to check for a low oil condition, the low oil module looks for a ground through the oil level switch. This is done after the ignition switch has been turned to the OFF or LOCK position.

The low oil module tests for a low oil condition as follows:
^ 32 minutes after the ignition switch is turned to the OFF or LOCK position, if the previous ignition cycle was less than 12 minutes
^ 3 minutes after the ignition switch is turned to the OFF or LOCK position, if the previous ignition cycle was longer than 12 minutes.

When the oil level is low, the low oil module loses the ground through the oil level switch. This means that the oil level switch is open, indicating low oil level. This action causes the low oil module to ground the LOW OIL indicator for the duration of the next ignition cycle.

When the low oil module is grounded through the oil level switch, the low oil module ground the LOW OIL indicator. This allows a bulb test when the ignition switch is turned to the RUN position during the next ignition cycle. The bulb test takes 4-5 seconds.