I really dunno what causes this issue I've been having ever sense I got a new transmission.... Well anyways this is what happens: When I have my headlights on and fan blower on mid or high settings. The temperature gauge goes pass the halfway mark almost to the 3/4 mark. My temp gauge before the new transmission was always on a quarter mark and didn't even make it to the halfway mark. Each time this happens the transmission doesn't want to shift out of first into second no matter what. When that happens I have to pull over and disconnect the black battery cable and reconnect it. Then the transmission starts to shift again. It does this about 1-2 times a day or sometimes more. I keep getting the run around at the transmission shop the transmission came from. Saying that its an electrical problem, but from what I was told at another shop that tested the electrical system that it sounds like a sensor inside the transmission. I really have no clue what's going on. Any help would be gratefully helpful. Thanks.

P.S. Forgot to add that even without the headlights on and just the fan blower it still happens or the other way around. And thanks again.