Circuit Description
The engine oil level switch is a float switch that is grounded when the engine oil level is OK. The PCM checks engine oil level at startup. 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 startup, the following conditions must be present:
| • | Startup engine coolant temperature must be greater than 15° C (59° F). |
| • | Startup engine coolant temperature must be at least 12° C (22° F) cooler than the engine coolant temperature was at the last key OFF. |
The low engine oil level lamp will be illuminated for about a minute when the PCM checks for low oil level and the engine oil level switch indicates that a low oil level condition exists (engine oil level switch circuit not grounded). When the ignition is first turned ON, the PCM commands the low engine oil level lamp ON for a brief period of time to test the bulb.
Diagnostic Aids
For diagnosis of the instrument panel, refer to the Instrument Panel System Check in Electrical Diagnosis.
Check for the following conditions:
| • | Poor connection at the PCM or the engine oil level switch. |
| Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and 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 the ignition ON. Observe a digital multimeter connected to measure voltage on the affected circuit while moving connectors and wiring harnesses related to the engine oil level switch. A change in voltage will indicate the location of the fault. |
| • | Low engine oil level lamp control circuit. |
| If a problem with the low engine oil level lamp can not be isolated using the Engine Oil Level Switch diagnostic table, refer to Powertrain Control Module Controlled Warning Lamps Diagnosis . |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart.
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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.
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For the PCM to check engine oil level, startup engine coolant temperature must be at least 12° C (22° F) cooler than the engine coolant temperature was last time the ignition was turned OFF. Allowing the engine to warm and then cool ensures that the PCM checks the engine oil level switch and that the information displayed on the scan tool is current.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Ensure that engine oil level is not low (as indicated on engine oil level indicator) before continuing diagnosis. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 | Observe Engine Oil Level displayed on the scan tool. Does Engine Oil Level display OK? | -- | Go to Powertrain Control Module Controlled Warning Lamps Diagnosis | |
3 |
Is the test light ON? | -- | ||
4 |
Does the DVM display voltage near the specified value? | B+ | ||
5 | Connect the digital multimeter to measure voltage between the engine oil level switch signal circuit and chassis ground. Does the digital multimeter display a voltage near the specified value? | B+ | ||
6 |
Was a problem found? | -- | Refer to Diagnostic Aids | |
7 |
Was a problem found? | -- | ||
8 |
Was a problem found? | -- | ||
9 | Locate and repair open in the engine oil level switch ground circuit (CKT 451). Refer to Repair Procedures in Electrical Diagnosis. Is action complete?. | -- | -- | |
10 | Replace the engine oil level switch. Refer to Engine Oil Level Switch . Is action complete? | -- | -- | |
Replace the PCM. Important: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is action complete? | -- | -- | ||
Does Engine Oil Level display OK? | -- | System OK |
