Diagnostic Procedure
WARNING: This page is about a different car, the 2002 Dodge Intrepid, 2002 Chrysler Intrepid, 2002 Chrysler Concorde, and 2002 Chrysler 300M. However, it is still accessible from the selected car via links, so may be relevant.
If DTC P1790 is set, transaxle should be diagnosed based on associated speed ratio error DTC. A repeatedly set DTC P1790 indicates problem is mechanical in nature.