My transmission began to not shift out of nowhere so I got diagnostic run on it and a code for the transmission came up and it shows that is the transmission relay on the firewall needs to be replaced. I replaced the relay and the car started to shift again I cut it off and shortly after I started the car up again and it started the problem again not shifting gears. Is there a short causing the relays to not work properly? Do i need to erase the codes after i replace the relays on the firewall cause i heard that might help? If anyone can help me please let me know.