GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The fuel rail pressure (FRP) sensor is a pressure sensor. The powertrain control module (PCM) supplies about 5 volts on the FRP sensor reference voltage circuit. The PCM also supplies a ground circuit and a signal circuit to the FRP sensor. When the fuel rail pressure is normal, the FRP signal voltage rises to near 2.5 volts. If the fuel rail pressure increases, the FRP signal voltage increases. The PCM uses the FRP sensor data in order to adjust fuel trim.

This DTC sets when the FRP sensor signal voltage is outside of the normal operating range of the sensor.

Conditions for Running the DTC

    • DTCs P0005, P0192, P0193, P0336, P1207, P1432, P1433, or P2665 are not set.
    • The CNG fuel tank pressure is more than 1 723 kPa (250 psi).
    • The ECT is more than 20°C (68°F).
    • The engine speed is more than 100 RPM.
    • The mass airflow (MAF) is less than 200 g/s.

Conditions for Setting the DTC

    • The FRP sensor is less than 206 kPa (30 psi), or more than 620 kPa (90 psi).
    • The condition exists for at least 3 seconds.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module switches over to gasoline fuel operation.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

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.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if the condition is present.

  2. This step determines if the low pressure lock-off (LPL) solenoid is functioning.

  3. This step tests the low reference circuit of the FRP sensor.

  4. This step determines if the 5-volt reference circuit is the cause of the condition. The DMM should display 5.0 volts across the test lamp.

  5. This step tests the signal circuit of the FRP sensor.

  6. This step verifies that a mechanical fuel system condition is not the cause of the concern. A fuel pressure regulator condition may cause this DTC to set.

Step

Action

Value(s)

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check Alternative Fuels - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Alternative Fuels (Engine Controls)

2

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the Fuel Rail Pressure (FRP) data display with a scan tool.

Does the scan tool display the FRP sensor pressure within the specified range?

206-1 620 kPa (30-90 psi)

Go to Step 3

Go to Step 4

3

  1. Observe the Freeze Frame and/or the Failure records data for this DTC.
  2. Turn the ignition OFF for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame and/or the Failure records data.

Does the DTC fail this ignition cycle?

--

Go to Step 4

Go to Intermittent Conditions

4

  1. Turn ON the ignition with the engine OFF.
  2. Command the LPL ON and OFF with a scan tool.
  3. Listen for operation of the LPL.

Can operation of the LPL be heard?

--

Go to Step 5

Go to DTC P2665

5

  1. Disconnect the FRP sensor. Refer to Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement .
  2. Probe the low reference circuit of the FRP sensor with a test lamp connected to B+.

Is the test lamp illuminated?

--

Go to Step 6

Go to Step 10

6

  1. Probe the 5-volt reference circuit of the FRP sensor with a test lamp to ground.
  2. Measure the voltage drop across the test lamp with a DMM. Refer to Measuring Voltage Drop in Wiring Systems in the C/K Pickup Service Manual.

Is the voltage at the specified value?

5.00 V

Go to Step 7

Go to Step 11

7

  1. Connect a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit of the FRP sensor.
  2. Observe the FRP sensor data display with a scan tool.

Does the scan tool display FRP sensor voltage more than the value specified?

4.95 V

Go to Step 9

Go to Step 8

8

Test the signal circuit of the FRP sensor for an open or excessive resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

9

Important: Return to this diagnostic procedure, after performing the Fuel System Diagnosis.

Perform the Fuel System Diagnosis procedure. Refer to Fuel System Diagnosis .

Did find and correct the condition?

--

Go to Step 15

Go to Step 13

10

Test the low reference circuit of the FRP sensor for excessive resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

11

Test the 5-volt reference circuit of the FRP sensor for excessive resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

12

Inspect for proper terminal contact at the harness connector of the FICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

13

Replace the fuel rail pressure sensor. Refer to Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement .

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the PCM. Refer to Powertrain Control Module Replacement in the C/K Pickup Service Manual.

Did you complete the replacement?

--

Go to Step 15

--

15

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30  seconds.
  3. Turn ON the ignition, with the engine OFF.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 16

16

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK