P0088

P0088-FUEL RAIL PRESSURE TOO HIGH





For complete wiring diagrams refer to Diagrams/Electrical.


Theory of Operation

The ECM will turn on the MIL lamp immediately after the diagnostic runs and fails. During this time the ETC lamp will also illuminate. The ECM will turn off the MIL lamp after the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:

Engine running.

- Set Condition:

Fuel pressure is above a calibrated value for a calibrated amount of time.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test


1. Fuel Pressure Sensor

Using the scan tool, compare the scan tool reading for fuel pressure set point to the scan tool reading for actual fuel pressure.

Is the pressure within ± 500 psi of set point?

No - Higher

- Go To 4

No - Lower

- Go To 2

Yes

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition

2. LIFT PUMP

Perform "*IN-TANK FUEL LIFT PUMP FLOW TEST - DIESEL". In-Tank Fuel Lift Pump Flow/Diagnostic Test Procedure

Did vehicle pass the *IN-TANK FUEL LIFT PUMP FLOW TEST - DIESEL?

Yes

- Go To 3

No

- Repair the Lift pump.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

3. INJECTOR RETURN FLOW

Perform the INJECTOR RETURN FLOW TEST - DIESEL. Injector Return Flow Test

Did vehicle pass the *INJECTOR RETURN FLOW TEST - DIESEL test?

Yes

- Go To 4

No

- Repair the fuel system as necessary.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. FUEL PUMP





Turn the ignition off.

Disconnect the Electronic Fuel Control Actuator connector.

Connect an incandescent test light across the Fuel Control Actuator driver circuit and the Fuel Control Actuator return circuit at the fuel control actuator harness connector.

Turn the ignition on.

Observe the test light.

The ECM will perform a self test of the circuit which should momentarily flash the test light brightly, one time, approximately 20 seconds after being connected.


NOTE: Compare test light brightness to that of a direct connection to the battery.

Did the light flash brightly?

Yes

- Replace the fuel pump.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition