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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 452 (Engine Controls - Self-Diagnostics - 6.0L Bi-Fuel & CNG) >> Diagnostic Tests >> DTC P0005: Fuel Shutoff Valve "A" Control Circuit/Open >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 GMC Sierra and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Alternative Fuels - Engine Controls. If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ALTERNATIVE FUELS - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn ignition on, with engine off. Command the High Pressure Lock-Off (HPL) relay on and off using a scan tool. If the HPL relay responds to the commanded state, go to next step. If HPL relay does not respond to the commanded stated, go to step  4.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn the ignition off for 30 seconds. Turn ignition on, with engine off. 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 cycle? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Turn ignition off. Disconnect the HPL relay. Turn ignition on, with engine off. Probe the HPL relay ignition voltage circuit with a test light that is connected to a good ground. If the test light illuminates, go to next step. If test light does not illuminate, go to step  9.
  5. Connect a test light between the HPL relay control circuit and the HPL relay ignition voltage circuit. Command the HPL relay on and off using a scan tool. If the test light turns on and off with each command, go to step  10. If test light does not turn on and off with each command, go to next step.
  6. If the test light remains illuminated with each command, go to step  8. If the test light does not remain illuminated with each command, go to next step.
  7. Test the HPL relay control circuit for an open or for a short to voltage. Did you find and correct and open or a short? If yes, go to step  14. If no, go to step  11.
  8. Test the HPL relay control circuit for a short to ground. Did you find and correct a short to ground? If yes, go to step  14. If no, go to step  13.
  9. Test the ignition voltage circuit for an open or short to ground. Did you find and correct an open or short to ground? If yes, go to step  14. If no, see ALTERNATIVE FUEL LOCK-OFF RELAY under MODULES, MOTORS, RELAYS & SOLENOIDS in SYSTEM & COMPONENT TESTING - 6.0L CHEVY EXPRESS, SAVANA, SIERRA & SILVERADO - BI-FUEL & CNG article.
  10. Test for an intermittent and/or a poor connection at the HPL solenoid. Did you find and correct an intermittent and/or a poor connection? If yes, go to step  14. If no, go to step  12.
  11. Test for an intermittent and/or a poor connection at the PCM. Did you find and correct an intermittent and/or a poor connection? If yes, go to step  14. If no, go to step  13.
  12. Replace the HPL solenoid. After replacement is complete, go to step  14.
  13. Replace the PCM. See After replacement is complete, go to next step.
  14. Observe the Freeze Frame/Failure Records for this DTC. Turn the ignition off for 30 seconds. Turn ignition on, with engine off. 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 cycle? If yes, go to step  2. If no, go to next step.
  15. Observe the Capture Info using a scan tool. Are there any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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