2002 neon transmission only 1st and reverse

The car was running fine, stopped for gas and when I started up the road I noticed it was not shifting out of 1st gear. pulled over and checked the fluid. It was fine, maybe a little brown but mostly red. I drove it home doing 30 mph. it goes into reverse fine, when i put it into drive it thumps harder then normal. It sounds like it is in "limp mode" and im wondering what the next step would be. I have checked the electrical connections on the transmission, they seem to be in good shape, checked the grounding strap that goes to the pcm/tcm just infront of transmission, it is there and looks to be ok.
thanks for any help.

Thanks for all the help! I decided not to wait for a response from the forum members or moderators (a good decision). Ended up having a friend with a scan tool read the codes and went ahead and replaced the trans control soeil. That was the ticket.
1 qt. atf-4 5 dollars
1 control valve 100 dollars
1 membership to this forum worthless
The balls and brains to figure things out for yourself PRICELESS