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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 92 (Engine Controls - Self-Diagnostics - 6.6L Diesel) >> Diagnostic Tests >> DTC P0090: Fuel Rail Pressure Sensor Current Out Of Range >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Is DTC U1800 present also? If yes, diagnose DTC U1800. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If no, go to next step.
  3. Attempt to start the engine. Does the engine start? If yes, go to next step. If no, go to step  5.
  4. Start the engine. Observe the Actual Fuel Rail Pressure and the Desired Fuel Rail Pressure with a scan tool. Does the scan tool display a pressure difference more than 5 MPa? If yes, go to step  6. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  5. Turn OFF the ignition. Disconnect the ECM connectors. Disconnect the FRP regulator connector. Measure the resistance from the control circuit of the FRP regulator to ground with a Digital Multimeter (DMM). Does the resistance measure infinite? If yes, go to step  15. If no, go to step  13.
  6. Turn OFF the ignition. Disconnect the FRP regulator harness connector. Turn ON the ignition, with the engine OFF. Probe the supply circuit of the fuel rail pressure regulator with a J 34142-B Unpowered Test Lamp connected to a good ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  9.
  7. Turn OFF the ignition. Verify the FRP regulator harness connector is disconnected. Turn ON the ignition, with the engine OFF. Probe the control circuit of the FRP regulator with a test lamp connected to battery voltage. Does the test lamp illuminate? If yes, go to step  14. If no, go to next step.
  8. Disconnect the ECM connector containing the FRP regulator control circuit. Turn ON the ignition, with the engine OFF. Measure the voltage from the FRP regulator control circuit to a good ground with a DMM. Does the voltage measure 0 V? If yes, go to step  16. If no, go to step  12.
  9. Turn OFF the ignition. Disconnect the ECM connector C2. Turn ON the ignition, with the engine OFF. Probe the ignition 1 voltage circuit of the harness connector with a test lamp that is connected to a good ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  11.
  10. Test for an open in the FRP supply circuit between the ECM and the FRP regulator. If a problem is found, repair as necessary. Did you find and correct the condition? If yes, go to step  19. If no, go to step  17.
  11. Repair the open in the ignition 1 voltage circuit to the ECM. After repairs, go to step  19.
  12. Repair the short to voltage in the control circuit between the ECM and the FRP regulator. After repairs, go to step  19.
  13. Test for a short to ground in the control circuit between the ECM and the FRP regulator. Did you find and correct the condition? If yes, go to step  19. If no, go to step  18.
  14. Inspect for poor connections at the FRP regulator. Repair the wiring as necessary. Did you find and correct the condition? If yes, go to step  19. IF no, go to next step.
  15. Replace the FRP regulator. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  19.
  16. Test for an open in the control circuit between the ECM and the FRP regulator. Did you find and correct the condition? If yes, go to step  19. If no, go to next step.
  17. Inspect for poor connections at the ECM. Repair the wiring as necessary. Did you find and correct the condition? If yes, go to step  19. If no, go to next step.
  18. Replace the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram ECM. See ENGINE CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  19. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  20. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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