my 2002 transmission will back up but won't go forward
Year make and model please.
2002 jeep grand cherokee, v6
On my Jeep the shift solenoid failed, mine did have a code for it in the system, replaced the solenoid, serviced the tranny while I was there, and back on the road again. So see if you can rent or borrow a good scanner and see if you get a transmission shift solenoid code. There is also a video on you tube on how to replace it if you think you want to dive into this yourself.