Circuit Description
The PCM applies 12 volts, through a pull up resistor, to the Engine Oil Level (EOL) switch. The (EOL) Switch is a simple float switch that is grounded when the engine oil level is OK. With theproper engine oil level, the EOL switch voltage input to the PCM is pulled low. If a low oil level condition occurs, the EOL switch circuit is no longer grounded and the EOL switch voltage input to the PCM is pulled high). The PCM sends the EOL switch information via Class II serial data to the Instrument Panel Cluster (IPC). The IPC controls the Low Engine Oil Lamp.
The PCM checks the EOL switch circuit at startup. Before checking the state of the EOL 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 engine coolant temperature must be greater than 15°C (59°F) and at least 12°C (22°F) cooler than the the engine coolant temperature at the last key OFF.
Diagnostic Aids
For diagnosis of the instrument panel, perform the System Check in the Instrument Cluster section of Electrical Diagnosis.
Check for the following conditions:
| • | Poor connection at PCM or EOL 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 EOL switch and turn the ignition on. Observe a voltmeter connected to the EOL circuit while moving connectors and wiring harnesses related to the EOL circuit. A change in voltage will indicate the location of the fault. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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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. Refer to Powertrain Control Module Replacement/Programming .
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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 the engine oil level indicator) before continuing diagnosis. Was the 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 Diagnostic Aids | |
3 |
Is the test light ON? | -- | ||
4 |
Is the voltage near the specified value? | B+ | ||
5 | Connect the digital multimeter between the engine oil level switch signal circuit and chassis ground. Is the voltage near the specified value? | B+ | ||
6 |
Was a problem found? | -- | Go 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 Wiring Repairs in Wiring Systems. Is action complete? | -- | -- | |
10 | Replace the engine oil level switch. Refer to Engine Oil Level Sensor and/or Switch Replacement . Is action complete? | -- | -- | |
Replace the PCM. Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is action complete? | -- | -- | ||
Does Engine Oil Level display OK? | -- | System OK |
