A couple days ago I was driving my truck on the interstate for about 3 hours and when I first came to a stop and started again my truck was in second. I t wouldn't shift to first. After it sat for a while it was fine. Drove the next day no problems. A couple days later it did the same thing but is working fine again. Any Ideas? Fluid is fine. Shifts through all gears like it always has. It just doesn't want to go back to first gear sometimes even if I shift it to first. It's a real pain in the when your pulling a trailer. I smoked a lot of people trying to start out in second with a trailer

 

Been serviced lately? Might be a dirty filter.

 

Any DTC's?

 

Somebody has my code reader

 

 

My DTT tranny will do this when the pcm sees too high of voltage for it. i have a voltage regulator from bill and no probs