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Home >> Chevrolet >> 2003 >> Tracker 2D Utility, 4WD, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 2.0L >> Diagnostic Tests >> DTC P0455: EVAP System - Large Leak Detected >> Test Description

Test Description

The numbers below refer to the step numbers in the diagnostic procedures.

  1. 1 -  The Diagnostic System Check - Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
  2. 3 -  This step checks the operation of the FTP sensor. If the FTP sensor does not indicate about zero pressure when the fuel filler cap is removed, the FTP sensor or circuit might be faulty. The FTP sensor can be checked by using the diagnostics in DTC P0450.
  3. 5 -  This step uses tools from the EVAP pressure/purge cart diagnostic station, in order to determine whether EVAP control system is sealed sufficiently to be pressurized. Any leak that is found must be located and repaired before continuing with the diagnosis.
  4. 8 -  This step checks the components that supply manifold vacuum to the EVAP canister purge valve.
  5. 9 -  This step checks the operation of the EVAP canister purge valve. The duty cycle control of the EVAP canister purge valve is disabled by the PCM when any DTCs are stored and when engine speed is indicated.
  6. 10 -  This step checks the operation of the EVAP canister vent valve. The output control of the EVAP canister vent valve is disabled by the PCM when any DTCs are stored and when engine speed is indicated.
  7. 25 -  Clearing the DTCs by removing the DOME fuse also clears the PCM long term memory. Using the scan tool to clear DTCs leaves the long term memory active. DTC emitting diagnostics may not run to completion as expected unless the long term memory is cleared. Removal of the DOME fuse also clears the time display of the radio. The DTC P0455 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0455 appears in the Not Ran Since Code Cleared list, the DTC P0455 diagnostic has not yet run. When the DTC P0455 does not appear in the Not Ran Since Code Cleared list, the DTC P0455 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC P0455 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.
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