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. 2
   
   The FTP sensor reading indicated on the scan tool will vary with the surrounding barometric pressure.
3. 8
   
   The FTP sensor voltage will vary with the surrounding barometric pressure.
4. 9
   
   This step verifies that the FTP sensor is able to react to evaporative emission (EVAP) system pressure changes.
5. 11
   
   This step checks for a blockage or a restriction that can trap pressure inside the fuel tank.
6. 15
   
   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 P0451 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If DTC P0451 appears in the Not Ran Since Code Cleared list, the P0451 diagnostic has not yet run. When DTC P0451 does not appear in the Not Ran Since Code Cleared list, the P0451 diagnostic has run. If the MIL is NOT illuminated and there is no Pending DTC Status in DTC Information, the P0451 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. The DTC Information screen must be checked for Current or Pending status in order to determine the outcome of the diagnostic test involved.