GM Service Manual Online
For 1990-2009 cars only

DTC P0088 Without RPO CTF

Circuit Description

The common rail is installed on the intake manifold, and is equipped with a flow damper, pressure limiter, and common rail pressure sensor.

The common rail unit has a common fuel passage and fuel passage holes. The common rail pressure sensor is installed at the left end of the unit.

The engine control module (ECM) monitors the common rail pressure signals for voltage outside the normal range of 10-104 kPa (1.5-15 psi) of the rail pressure sensor. If the ECM detects a common rail pressure signal voltage that is excessively low, this DTC will set.

Conditions for Running the DTC

    • The battery voltage is more than 8 volts.
    • The fuel injection pump speed is more than 450 RPM.
    • The coolant temperature is 60°C (140°F) or more.
    • DTC P0190, P0192, or P0193 is not set.

Conditions for Setting the DTC

Common rail pressure is more than 10 MPa (1,450 psi) over the target pressure.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The ECM limits fuel delivery.

Conditions for Clearing the MIL/DTC

    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

Inspect for the following conditions:

    • Poor connection at the ECM
        Inspect the harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.
    • Damaged harness
        Inspect the wiring harness for damage, shorts to ground, shorts to battery, and open circuits. If the harness appears to be OK, observe the Rail Pressure display on the scan tool while moving connectors and wiring harnesses related to the common rail pressure sensor. A change in the common rail pressure scan tool display will indicate the location of the fault.

Step

Action

Value

Yes

No

Schematic Reference: Engine Controls Schematics

1

Does the DTC set while the engine is running?

--

Go to Step 2

Go to Diagnostic Aids

2

  1. Turn OFF the ignition.
  2. Disconnect the rail pressure sensor harness connector from the PC sensor.
  3. Start and idle the engine.
  4. Measure the voltage between pin number 2 (PFUEL) and pin number 3 (PFUEL - GND) of the PC sensor harness connector with ECT more than 60°C (140°F).

Does the voltage measure more than the specified value?

1.4 V

Go to Step 6

Go to Step 3

3

  1. Connect the rail pressure sensor harness.
  2. Clear all DTCs.

Does the DTC reset?

--

Go to Step 5

Go to Step 4

4

Inspect for a poor connection at the rail pressure sensor harness connector.

Is the connection good?

--

System OK

Go to Step 9

5

  1. Inspect for any DTCs for CKP/CAM sensor.
  2. Inspect for proper installation of the fuel injection pump.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 7

6

  1. Turn OFF the ignition.
  2. Disconnect the rail pressure sensor harness from the sensor and the ECM.
  3. Measure the resistance of the following circuits:
  4. • The rail pressure sensor 1 signal
    • The rail pressure sensor 2 signal
    • The rail pressure sensor ground

Does each resistance measure less than the specified value?

2 ohms

Go to Step 7

Go to Step 10

7

Measure the resistance of the following circuits to ground:

    • The rail pressure sensor 1 signal
    • The rail pressure sensor 2 signal
    • The rail pressure sensor ground

Does each resistance measure more than the specified value?

10 M ohms

Go to Step 8

Go to Step 11

8

  1. Reconnect the rail pressure sensor harness to the sensor and the ECM.
  2. Clear all DTCs, then start the engine.
  3. Press and release the accelerator pedal several times.

Does the DTC reset?

--

Go to Step 13

Go to Step 12

9

Repair the rail pressure sensor wiring harness.

Did you complete the repair?

--

Go to Step 14

--

10

Repair/replace or correct connections of the rail pressure sensor harness connector.

Did you complete the action?

--

Go to Step 14

--

11

Repair the rail pressure sensor harness short to ground.

Did you complete the repair?

--

Go to Step 14

--

12

Replace the rail pressure sensor harness.

Did you complete the replacement?

--

Go to Step 14

--

13

Replace the rail pressure sensor.

Did you complete the replacement?

--

Go to Step 14

--

14

Clear all DTCs then operate the vehicle within the conditions to run the DTC.

Does the DTC reset?

--

Go to Step 15

Go to Step 17

15

Replace the ECM.

Did you complete the replacement?

--

Go to Step 16

--

16

Clear all DTCs then operate the vehicle within the conditions to run the DTC.

Does the DTC reset?

--

Go to Step 2

Go to Step 17

17

Do any other DTCs set?

--

Go to Diagnostic Trouble Code (DTC) List

System OK