The tranny goes into what

There are several causes why your tranny goes into fail safe. This happens when the ECU detects that something is wrong the the tranny.

One thing you can check is the flow of electricity. In some cases, when this happens, something unusual happens with the electrical devices inside the car, like power windows not working correctly. First thing that you can check are the terminals to the batteries and have the battery and alternator tested. Check also the wiring if the connections are still OK.

Other sources of this error is something wrong with the ATF. In some cases there are ATF fuids that may have dried up or got burned. In this case, replacing the oil would be needed.

Another is the fluid pressure may not be correct. If the last suggestion on the oil does not work, check the solenoid if it is OK. It controls the oil pressure that lets you shift into different gears. See if it is still working correctly or if it just needs a a good cleaning.