Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Ensure that the reference port on the FTP sensor is unobstructed.
Scan tool output controls, snapshot, and the plot function can help detect erratic sensor operation. To observe the Fuel Tank Pressure Sensor signal under vacuum conditions, use the Quick Snapshot and the EVAP Purge/Seal function to capture data while commanding purge to 20 percent. Then plot the data to look for erratic sensor operation. A similar test can be done for the pressure side of the sensor range by applying pressure with J 41413-200 Evaporative Emission System Tester (EEST) while taking a snapshot with the scan tool. See Special Tools .