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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 P1208: Fuel Rail Temperature 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 FICM even bank circuit status. Does the scan tool display FAULT? If yes, go to next step. If no, go to step  4.
  3. Are any of the DTCs P0187, P0188, P0191, P0192, P0193, or P0611 also set? 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 FRT sensor harness connector. Turn ignition on, with engine off. Measure the voltage from the signal circuit of the FRP sensor with a DVOM. Does the DVOM display a voltage near 5.0 volts? If yes, go to step  7. If no, go to next step.
  6. If the voltage is above 5.3 volts, go to step  14. If the voltage is below 5.3 volts, go to step  13.
  7. Probe the FRT sensor low reference circuit with a test light connected to battery positive. If the test lights illuminates, go to next step. If the test light does not illuminate, go to step  15.
  8. Using a scan tool, observe the FRT sensor temperature parameter. Jumper the FRT sensor signal circuit to a good ground. If the FRT temperature display fluctuates when the circuit is grounded, go to step  16. If the FRT temperature display does not fluctuate when the circuit is grounded, go to next step.
  9. Turn ignition off. Connect the FRT sensor harness connector. Disconnect the PCM harness connector C2. Turn ignition on, with engine off. Measure the voltage from the rail temperature output PWM circuit with a DVOM. Does the DVOM display 5.0 volts? If yes, go to step  17. If no, go to next step.
  10. If the voltage is more than 5.3 volts, go to step  12. If the voltage is less than 5.3 volts, go to next step.
  11. Test for an open or a short to ground on the rail temperature output PWM circuit. Did you find and correct an open or a short to ground? If yes, go to step  22. If no, go to step  18.
  12. Test for a short to voltage on the rail temperature output PWM circuit. Did you find and correct a short to voltage? If yes, go to step  22. If no, go to step  21.
  13. Test for an open on the FRT sensor signal circuit. Did you find and correct an open? If yes, go to step  22. If no, go to step  18.
  14. Test for a short to voltage on the FRT sensor signal circuit. Did you find and correct a short to voltage? If yes, go to step  22. If no, go to step  21.
  15. Test for an open on the FRT sensor low reference circuit. Did you find and correct an open? If yes, go to step  22. If no, go to step  18.
  16. Test for an intermittent and/or a poor connection at the FRT sensor. Did you find and correct an intermittent and/or a poor connection? If yes, go to step  22. If no, go to step  19.
  17. Inspect for proper terminal contact at the harness connector of the PCM. Did you find and correct an intermittent and/or a poor connection? If yes, go to step  22. If no, go to step  20.
  18. 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  22. If no, go to step  21.
  19. Replace the FRT sensor. After replacement is complete, go to step  22.
  20. Replace the PCM. After replacement is complete, go to step  22.
  21. Replace the FICM. After replacement is complete, go to next step.
  22. 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.
  23. 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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