LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 448 (Engine Controls Self-Diagnostics - 6.0L Bi-Fuel & CNG) >> Diagnostic Tests >> DTC P1207: Fuel Rail Pressure Output PWM Signal Not Received By Pcm >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 GMC Savana and 2003 Chevrolet Chevy Express. 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. Using a scan tool, observe the Fuel Injection Control Module (FICM) odd bank circuit status. Does the scan tool display FAULT? If yes, go to next step. If no, go to step  4.
  3. Do any of the DTCs P0187, P0188, P0191, P0192, P0193, or P0611 also set this ignition cycle? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to step  5.
  4. Observe the Freeze Frame and/or the Failure records data for this DTC. Turn the ignition off for 30 seconds. Start the engine. 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. If the DTC failed this ignition cycle, go to next step. If the DTC does not fail this ignition cycle, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  5. Turn ignition off. Disconnect the FRP sensor harness connector. Turn ignition on, with engine off. Using a scan tool, observe the FRP sensor pressure parameter. Does the scan tool display a pressure of 0 psi (0 kPa)? If yes, go to step  8. If no, go to next step.
  6. Measure the FRP sensor voltage from the 5-volt reference circuit with a DVOM. Does the DVOM display a voltage near 5.0 volts. If yes, go to next step. If no, go to step  14.
  7. Probe the FRP sensor low reference circuit with a test light connected to battery positive. If the test light illuminates, go to step  18. If test light does not illuminate, go to step  15.
  8. Measure the voltage from the signal circuit of the FRP sensor. If the DVOM displays less than 1.0 volt, go to next step. If the DVOM displays more than 1.0 volt, go to step  17.
  9. Using a DVOM, measure the resistance of the FRP sensor signal circuit to a good ground. If the DVOM displays OL, go to next step. If the DVOM does not display OL, go to step  16.
  10. Turn ignition off. Connect the harness connector of the FRP sensor. Disconnect the PCM harness connector C1. Turn ignition on, with engine off. Measure the voltage from the rail pressure output PWM circuit with a DVOM. If the DVOM displays 5.0 volts, go to step  19. If the DVOM does not display 5.0 volts, go to next step.
  11. If the voltage is more than 5.3 volts, go to step  13. If the voltage is less than 5.3 volts, go to next step.
  12. Test for an open, or a short to ground on the rail pressure output PWM circuit. Did you find and correct an open or a short to ground? If yes, go to step  24. If no, go to step  20.
  13. Test for a short to voltage on the rail pressure output PWM circuit. Did you find and correct a short to voltage? If yes, go to step  24. If no, go to step  23.
  14. Test for an open, or a short to ground on the FRP sensor 5 volt reference circuit. Did you find and correct an open or a short to ground? If yes, go to step  24. If no, go to step  20.
  15. Test for an open on the FRP sensor low reference circuit. Did you find and correct an open? If yes, go to step  24. If no, go to step  20.
  16. Test for a short to ground on the FRP sensor signal circuit. Did you find and correct a short to ground? If yes, go to step  24. If no, go to step  23.
  17. Test for a short to voltage on the FRP sensor signal circuit. Did you find and correct a short to voltage? If yes, go to step  24. If no, go to step  23.
  18. Test for an intermittent and/or a poor connection at the FRP sensor. Did you find and correct an intermittent and/or a poor connection? If yes, go to step  24. If no, go to step  21.
  19. 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  24. If no, go to step  22.
  20. Test for an intermittent and/or a poor connection at the FICM. Did you find and correct an intermittent and/or a poor connection? If yes, go to step  24. If no, go to step  23.
  21. Replace the FRP sensor. After replacement is complete, go to step  24.
  22. Replace the PCM. After replacement is complete, go to step  24.
  23. Replace the FICM. After replacement is complete, go to next step.
  24. Using a scan tool, clear the DTCs. Turn ignition off for 30 seconds. Start the engine. 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. If the DTC failed this ignition cycle, go to step  2. If the DTC did not fail this ignition cycle, go to next step.
  25. 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.
scientia non olet · About LEMON Manuals