Chart C-16 Oil Level Input

Chart C-16 Oil Level Input:

PCM Sensor Inputs:

CIRCUIT DESCRIPTION
A "Check Oil" lamp, located in the Instrument Panel Cluster (IPC), is illuminated when low engine oil level is detected. The Powertrain Control Module (PCM) receives a signal from the engine oil level switch located in the engine oil pan. The engine oil level switch is closed when the engine oil level is "OK." The PCM then sends a message to the IPC over serial data telling the IPC whether to illuminate "Check Oil" lamp. The PCM first checks for engine oil level when the ignition is "OFF." If low engine oil level is detected, the engine oil level switch is open and the PCM will then wait for 10 minutes before determining if the engine oil level is low or if the engine oil is still returning to the engine oil pan. When the ignition is turned "ON," the PCM will then tell the IPC to turn "ON" the "Check Oil" lamp if engine oil level is still indicated as "Low." Once the ignition is cycled "OFF," the PCM will wait for another 10 minute cycle to be competed before telling the IPC to turn "ON" the "Check Oil" lamp. The PCM will check engine oil level only once per ignition "OFF" and ignition "ON" cycle.

"Check Oil" lamp will be illuminated when:

^ Ignition "OFF" logic has detected low engine oil level.
^ Ignition "ON" logic has detected low engine oil level.
^ Ignition has been "OFF" for 10 minutes.
^ All above conditions have been satisfied.

CHART TEST DESCRIPTION
Number(s) below refer to step numbers on the diagnostic chart.

1. The Tech 1 scan tool is useful in diagnosing the engine oil level switch and circuitry. The Tech 1 will react quickly to oil level changes and therefore does not reflect when the "Check Oil" lamp is illuminated.
2. Probing cavity "B" (CKT 1174) of the engine oil level switch electrical connector simulates "OK" oil level. The Tech 1 scan tool will display oil level as "OK" while being probed. If the test light illuminates, then the circuit is shorted to voltage or the PCM is faulty.
3. Disconnecting the engine oil level switch electrical connector simulates "Low" oil level. If the Tech 1 scan tool displays engine oil level as "OK," then CKT 1174 is shorted to ground or the PCM is faulty.

DIAGNOSTIC AIDS
The IPC will illuminate the "Check Oil" lamp for 3 seconds at ignition "ON" to check the bulb. If the "Check Oil" lamp does not illuminate for 3 seconds and then go out or is illuminated continuously after several key "ON" cycles less than 10 minutes apart, refer to Instrument Panel, Gauges and Warning Indicators. Instrument Panel, Gauges and Warning Indicators

An "Intermittent" problem may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.

Any circuitry that is suspected as causing the intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.