GMC Repair: cadillac tranny solenoids, auto part store, code scanner

Question
i have a Cadillac sedan Seville 93' and my transmission has trouble when it gets to around 25-30 mph and wont shift after that could it be a solenoid?

Answer
it could be that, or the wiring harness within. you will definitely need a code scanner. you can pick one up at your local auto part store. they range from about 30-200 dollars. I can only give you a basic idea of what it could or may be without scanning or looking up the codes myself. hope this helps. Generally, it is the solenoid or the wiring harness with this type of problem.