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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 213 (Engine Controls - Self-Diagnostics - 3.0L) >> Diagnostic Tests >> DTC P0451: EVAP Fuel Tank Pressure Sensor Performance >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Saturn Vue. 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, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS .
  2. Monitor the FTP sensor voltage with the scan tool, with the fuel cap removed. Is the FTP sensor value within 1.0-2.85 volts? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING 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? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  4. Turn ignition on, with engine off. Disconnect the fuel tank harness connector. Measure the voltage from 5-volt reference circuit of the FTP sensor at the fuel tank harness connector, the control module side, to a good ground with a DVOM. Is the voltage about 5 volts? If yes, go to next step. If no, go to step  6.
  5. Measure the voltage from the 5-volt reference circuit to the low reference circuit at the fuel tank harness connector, the control module side, with a DVOM. Is the voltage about 5 volts? If yes, go to step  8. If no, go to step  7.
  6. Test the 5-volt reference circuit of the FTP sensor for an open or short to ground between the harness connector and the control module. Did you find and correct the condition? If yes, go to step  13. If no, go to step  10.
  7. Test the low reference circuit of the FTP sensor for an open or for high resistance between the harness connector and the control module. Did you find and correct the condition? If yes, go to step  13. If no, go to step  10.
  8. Remove the fuel tank. Inspect the fuel tank wiring harness for damage, shorts, and high resistance in the FTP harness from the fuel tank wiring harness connector to the FTP sensor. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
  9. Inspect for poor connections at the FTP sensor harness connector and the fuel tank harness connector. Did you find and correct the condition? If yes, go to step  13. If no, go to step  11.
  10. Inspect for poor connections at the harness connector of the control module. Did you find and correct the condition? If yes, go to step  13. If no, go to step  12.
  11. Replace FTP sensor. After replacing sensor, go to step  13.
  12. Replace ECM. Perform ECM relearn procedures. See ENGINE CONTROL MODULE  under PROGRAMMING. After replacing ECM, go to next step.
  13. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING 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? If yes, go to step  2. If no, go to next step.
  14. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
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