Dear Doctor: I have a 1989 Ford Crown Victoria. The transmission’s overdrive went out, although the other gears work correctly. We replaced the transmission with another one from a scrap yard, but the overdrive still does not work. What is causing the problem in the shifter or linkage? Fred
Dear Fred: Before any parts are replaced, the trouble flow chart needs to be followed. There is a “check list” that needs to be followed, too. This can be obtained through the Alldata web site. I have seen many mismatched transmissions replaced in all types of vehicles. These mismatched transmissions will fit right in, however, they will not have all the features that the correct transmission will have. At this point you need to take the car to a transmission expert who will need to check the transmission and application.