Engine Oil Level Sensor/Switch Diagnosis

Diagnostic Chart:

Schematic:

CIRCUIT DESCRIPTION
The engine oil level switch is a simple float switch that is grounded when the engine oil level is OK. The Powertrain Control Module (PCM) checks the Engine Oil Level switch circuit at start-up. Before checking the state of the engine oil level switch, the PCM performs a test routine based on time and engine coolant temperature to ensure that the engine oil has drained back into the sump. To test for low oil level at start-up, one of the following conditions must be present:
^ If the engine coolant temperature was between 15°C-130°C (59°F-266°F) at the last key OFF, the engine coolant temperature at key ON must be at least 12°C (22°F) cooler than the engine coolant temperature at the last key OFF.
^ If the engine coolant temperature was higher than 82°C (150°F) at the last key OFF, the time between last key OFF and the present key ON must be sufficient to allow the oil to drain back to the sump. The PCM will remain powered up for 10 seconds to ensure that the oil has drained back to the sump. If the key is turned back ON while the PCM is still powered up, the oil level will not be tested.

The low oil level lamp will be illuminated for approximately 7 minutes when the PCM checks for low oil level and the engine oil level switch indicates that a low oil level condition exists. 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.

DIAGNOSTIC AIDS
For diagnosis of the instrument panel, perform A Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges, and Console. Diagnostic System Check - Instrument Panel Cluster

Check for the following conditions:
^ Poor connection at the PCM or oil level sensor - Inspect harness connectors for:
- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Poor terminal to wire connection
^ Damaged harness - Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the PCM and turn ON the ignition. Observe a voltmeter connected to the affected PCM output circuit while moving connectors and wiring harnesses related to the PCM output circuit. A change in voltage will indicate the location of the fault.
^ Engine Oil Level Switch circuit - If the problem with the low oil level lamp cannot be isolated using the Engine Oil Level Switch Diagnostic Table, use the PCM Controlled Lamps Diagnostic Table.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
14. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.