Not an A body but still Mopar NEED HELP!

To check faults in the TCM you will need a starscan or equal diagnostic tool, Will most likly need to be done at a dealer or professional repair shop. I'm going to guess it has a 545RFE Trans. I have seen a few times where the shift control module gets a short/locks up and locks up the TCM, this condition normaly goes away after restart because the modules reboot. Can be a tuff one to diag. if it is not acting up all the time. If it was mine I would check to system for faults and then continue to drive it to see if condition reoccurs. If you get any faults post them up and I'll do my best to help