For 1990-2009 cars

## Engine Oil Pressure Gage Inaccurate or Inoperative 8.1L Gas Engine L18

Step | Action | Value(s) | 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 | Start the engine. Does the engine oil pressure (EOP) gage display that the engine oil pressure is within the specified range? | 69-483 kPa (10-70 psi) | 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 PCM connector C2.
3. Turn the ignition ON, with the engine OFF.

Does the EOP gage display at or above the specified value?

550 kPa (80 psi)

Go to Step 4

Go to Step 6

4 |

1. Turn the ignition OFF.
2. Connect a 3 ampere fused jumper between the signal circuit of the EOP gage and a good ground.
3. Turn the ignition ON, with the engine OFF.

Does the EOP gage display at or below the specified value?

0 kPa (0 psi)

Go to Step 8

Go to Step 5

5 | Test the signal circuit of the EOP gage for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7
6 | Test the signal circuit of the EOP gage for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7
7 | Inspect for poor connections at the harness connector of the IPC. 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 11 | Go to Step 9
8 | 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 11 | Go to Step 10
9 | Replace the IPC. Refer to Instrument Cluster Replacement . Did you complete the replacement? | -- | Go to Step 11 | --
10 | Important: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 8.1L. Did you complete the replacement? | -- | Go to Step 11 | --
11 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2

## Engine Oil Pressure Gage Inaccurate or Inoperative 7.2L Diesel Engine LG5

Step | Action | Value(s) | 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 | Start the engine. Does the engine oil pressure (EOP) gage display that the engine oil pressure is within the specified range? | 69-483 kPa (10-70 psi) | 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 EOP sensor.
3. Turn the ignition ON, with the engine OFF.

Does the EOP gage display at or above the specified value?

550 kPa (80 psi)

Go to Step 4

Go to Step 6

4 |

1. Turn the ignition OFF.
2. Connect a 3 ampere fused jumper between the signal circuit of the EOP sensor and a good ground.
3. Turn the ignition ON, with the engine OFF.

Does the EOP gage display at or below the specified value?

0 kPa (0 psi)

Go to Step 7

Go to Step 5

5 | Test the signal circuit of the EOP sensor for an open, for a high resistance, or for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9
6 | Test the signal circuit of the EOP sensor for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9
7 | Test the ground circuit of the EOP sensor for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8
8 | Inspect for poor connections at the harness connector of the EOP sensor. 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 12 | Go to Step 10
9 | Inspect for poor connections at the harness connector of the IPC. 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 12 | Go to Step 11
10 | Replace the EOP sensor. Refer to the Cat® Medium Duty Diesel Manual - LG5. Did you complete the replacement? | -- | Go to Step 12 | --
11 | Replace the IPC. Refer to Instrument Cluster Replacement . Did you complete the replacement? | -- | Go to Step 12 | --
12 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2