While accelerating while passing my truck suddenly felt like it went into neutral and the check engine light came on. I slowed down to and was able to drive at approx 35-40mph with out any problems. I hooked it up to a scanner and got a code P0700 (transmission control system malfunction) and codes P0735, P0734 & P0733 (5th 4th and 3rd gear ratio incorrect). I'm almost convinced its the relay module but not sure.
Check battery for condition first including load test. Make sure terminal are clean so not to give false readings then check fluid level. This can also be an inputand output speed sensor problem or ground as well or an internal trans problem like a bad seal or clutch. A rans guy sold really scan this and give a better opinion