GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2002 🢒 Century 🢒 DTC 🢒 DTC P1189

Circuit Description

With low oil pressure, the engine oil pressure switch closes, and the signal circuit is low. With oil pressure above 4.5 psi, the engine oil pressure switch opens, and the signal circuit is high. The PCM monitors the oil pressure switch signal circuit and sends a class 2 message to the IPC indicating the switch status.

Conditions for Running the DTC
    • DTC P0117 is not set
    • DTC P0118 is not set.
    • DTC P1114 is not set.
    • The ignition is ON with the engine OFF.
    • The engine temperature at the last shutdown was at least 80°C (176°F).

Conditions for Setting the DTC
    • The PCM detects that the oil pressure switch signal circuit is high.
    • The above condition is present for greater than 10 seconds.

Action Taken When the DTC Sets

The PCM stores the conditions that are present when the DTC sets. The information is stored as Failure Records data only. This information is not stored as Freeze Frame data.

Conditions for Clearing the DTC
    • The DTC becomes history when then conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction free warm-up cycles.
    • The PCM receives the clear code command from the scan tool.

Step

Action

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the Instrument Cluster Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2
  1. Install a scan tool.
  2. Turn the ignition ON, with the engine OFF.
  3. With a scan tool, observe the Engine Oil Pressure Switch parameter in the PCM Engine Data 2 data list.

Does the Engine Oil Pressure Switch parameter display Low?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3
  1. Turn the ignition OFF.
  2. Disconnect the engine oil pressure switch.
  3. Connect a fused jumper wire between the oil pressure switch signal circuit and a good ground.
  4. Turn the ignition ON, with the engine OFF.
  5. With a scan tool, observe the Engine Oil Pressure Switch parameter in the PCM Engine Data 2 data list.

Does the Engine Oil Pressure Switch parameter display Low?

Go to Step 5

Go to Step 4

4

Test the signal circuit of the engine oil pressure switch for an open or a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 7

5

Test the ground circuit of the engine oil pressure switch for an open or a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 6

6

Inspect for poor connections at the harness connector of the engine oil pressure switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

7

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 9

8

Replace the engine oil pressure switch. Refer to Engine Oil Pressure Sensor and/or Switch Replacement or Engine Oil Pressure Sensor and/or Switch Replacement .

Did you complete the replacement?

Go to Step 10

--

9

Important: Program the replacement PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-3.1L or to Powertrain Control Module Replacement in Engine Control-3.8L.

Did you complete the replacement?

Go to Step 10

--

10
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

System OK

Go to Step 2