Originally Posted by
nene
I think there's two fundamentals that need looking at first and foremost.
Number one is the most important thing - whenever an auto is behaving even slightly weird, always check the fluid level first.
Then it's a good idea to do an AT ECU diagnostic to see if it's reporting any faults.
So when you say it starts warming up the transmission won't go into gear, how long does this take, in terms of either distance or time? Does it still do it if the car is left stationary with the engine running? If the transmission won't go into gear in D, what about other positions?
Troubleshooting is much easier when talking to the person with the problem directly.