Circuit Description
The powertrain control module (PCM) applies battery voltage through a pull up resistor to the engine oil pressure switch circuit. The PCM monitors the applied voltage on the engine oil pressure switch circuit. If the ignition switch is turned on with the engine not running, or the engine oil pressure is below 35 kPa (5 psi), the engine oil pressure switch grounds the PCM voltage input. The PCM sends the engine oil pressure information, via the Class 2 serial data, to the instrument panel cluster (IPC). The IPC controls the engine oil pressure indicator.
Diagnostic Aids
Inspect for the following conditions:
| • | Any faulty connections. Inspect the PCM and the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections. |
| • | Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the engine oil pressure switch, turn the ignition on and observe a voltmeter connected between the engine oil pressure switch connector terminals while moving the wiring harnesses related to the engine oil pressure switch circuit. A change in voltage indicates the location of the fault. |
Engine Oil Pressure Switch Diagnosis
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |||||
2 | Are any PCM DTCs stored? | -- | Diagnose the PCM DTC(s) first. | Go to Step 3 | ||||
3 | Is the engine oil pressure indicator illuminated? | -- | Go to Step 4 | Go to Step 16 | ||||
4 | Inspect the engine for the correct oil level. Is the engine oil level correct? | -- | Go to Step 5 | Go to Step 11 | ||||
5 | Test the engine oil pressure with a manual pressure gauge. Is proper engine oil pressure indicated? | -- | Go to Step 6 | Go to Step 12 | ||||
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 9 | ||||
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 10 | ||||
8 |
Are the terminal connections OK? | -- | Go to Step 13 | Go to Step 16 | ||||
9 |
Are the CKTs OK? | -- | Go to Step 15 | Go to Step 16 | ||||
10 | Locate and repair the following circuit conditions:
Did you complete the repair? | -- | Go to Step 16 | -- | ||||
11 | Determine the cause of low oil. Did you complete the repair? | -- | Go to Step 16 | -- | ||||
12 | Determine cause of low oil pressure. Did you complete the repair? | -- | Go to Step 16 | -- | ||||
13 | Test the communication circuit for correct operation. Refer to Wiring Repairs in Wiring Systems. Was a problem found? | -- | Go to Step 16 | Go to Step 14 | ||||
14 | Replace the engine oil pressure switch. Refer to Engine Oil Pressure Sensor/Switch Replacement . Did you complete the repair? | -- | Go to Step 16 | -- | ||||
15 |
Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the repair? | -- | Go to Step 16 | -- | ||||
16 | Test for the proper operation of the oil pressure indicator. Is the correct operation indicated? | -- | System OK | Go to Step 2 |
