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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 965 (Engine Controls Diagnosis - 6.6L (Lb7) (DTCS P0016 To P0236)) >> Diagnosis >> DTC P0088 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 3:  DTC P0090 is a current flow problem in the FRP regulator circuit. This incorrect current draw could lead to incorrect fuel pressure. This hardware problem should be diagnosed before the performance DTC is checked.
DTC P0088

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the Actual Fuel Rail Pressure parameter with a scan tool.
Is the Actual Fuel Rail Pressure parameter within the specified range?		 1-1.8 MPa Go to Step 3  Go to Step 6 
3  Did DTC P0090 also set? - Go to DTC P0090  Go to Step 4 
4
  1. Start the engine.
  2. Observe the Actual Fuel Rail Pressure on the scan tool.
  3. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or as close to the Freeze Frame/Failure Records data that you observed.
Is the Actual Fuel Rail Pressure more than the specified value?		 167 MPa Go to Step 11  Go to Step 5 
5
  1. Start and idle the engine.
  2. Perform the following test at idle and at 2,000 RPM:
    • Change the fuel pressure with a scan tool, incrementing through the entire fuel pressure range.
    • Observe the actual vs desired fuel pressures at each fuel pressure level.
Does the fuel pressure increment and stabilize through the entire fuel pressure range, with actual and desired fuel pressure within 2 MPa of each other at every fuel pressure?		 - Go to Diagnostic Aids Go to Step 11 
6
  1. Disconnect the fuel rail pressure (FRP) sensor.
  2. Observe the Actual Fuel Rail Pressure parameter with a scan tool.
Does the Actual Fuel Rail Pressure measure more than the specified value?		 175 MPa Go to Step 9  Go to Step 7 
7 Test the FRP sensor signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Step 8 
8 Replace the engine control module. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 12  -
9 Test the signal circuit of the FRP sensor for a high resistance or an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 13  Go to Step 10 
10 Replace the FRP sensor. Refer to Fuel Rail Pressure (FRP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 12  -
11 Replace the FRP regulator. Refer to Fuel Pressure Regulator Replacement .
Did you complete the replacement?		 - Go to Step 12  -
12
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC.
Does the DTC fail this ignition?		 - Go to Step 2  Go to Step 13 
13 With a scan tool, observe the stored information, Capture Info.
Does the scan tool display any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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