1999 Camry No reverse
 

Need help, I don't know whats wrong with my car. I lost reverse so I bought a used transmission with 70,000 miles on it from a respected recycle yard. When I had the tranny installed it worked for a little bit but when it warmed up it lost reverse also. I took the tranny back to the place I got it and they installed another one for me with even less miles and it's doing the same thing too. Please help, has this happened to anyone and do you know the fix?? Any help would be appreciated. Thanks for looking.:confused: