Refer to Engine Controls Schematics
PCM Engine Oil Level and Pressure Inputs
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Circuit Description
The low oil pressure sensor is normally closed. When oil pressure increases is above 1 to 4.5 psi the switch contacts open. The PCM supplies 12 volts to the oil pressure input circuit. With low oil pressure the 12 volts is pulled low to ground. This diagnostic tests for a open condition of the oil pressure switch circuit. If the engine has been off long enough for engine temperature to drop by 10°C, then a shorted (low oil pressure) condition of the circuit should be observed prior to engine running. If the engine has not been cranked and oil pressure has been detected. DTC P1189 will set.
Conditions for Running the DTC
| • | Codes P0117, P0118 and P1114 are not set. |
| • | The iIgnition is ON. |
| • | The engine is OFF. |
| • | The engine temperature is 10°C less than last key OFF temperature. |
Conditions for Setting the DTC
The circuit is open for 10 seconds
Action Taken When the DTC Sets
| • | The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | A History DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | The current DTC will clear when the diagnostic runs and does not fail. |
| • | Use a scan tool in order to clear the MIL diagnostic trouble code. |
| • | Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module Description , Clearing Diagnostic Trouble Codes. |
Diagnostic Aids
With the key on and the engine off the oil pressure display on the scan tool should indicate LOW. An open sensor or circuit would indicate OK with the key on and the engine OFF.
This DTC only tests the oil pressure circuit for an open condition.
If the problem is intermittent, Refer to Intermittent Conditions in Symptoms.
Test Description
An example test description follows:
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Checking to see if the fault is present. Low should be displayed with the engine not running.
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Checking to see if the oil pressure switch or wiring is at fault.
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Checking to see if the oil pressure switch input circuit or the PCM is at fault.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Does the scan tool indicate low oil pressure? | -- | Go to Diagnostic Aids | ||
Does the scan tool indicate oil pressure low? | -- | |||
Is the resistance the same or less than the value specified? | 5 ohms | |||
5 | Repair the open in either the oil pressure sensor input circuit or the oil pressure sensor ground circuit. Refer to Wiring Repairs . Did you find and correct the condition? | -- | -- | |
6 | Inspect for poor connections at the harness connector of the oil pressure sensor connector. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
7 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
8 | Replace the oil pressure sensor. Did you complete the replacement? | -- | -- | |
9 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | |
10 |
Does the DTC reset? | -- | System OK |
