voltage change doesnot effect the problem temp does u can put a charger on battery when its cold, code doesnot go away. start car let it warm up shut it off then it wil clear that is what i have found

 

update so it was about 70 degrees for a few days week or so ago and the car fixed itself now thats it cold it came back but if u start it let it run say 5 mins u can clear it and all good so that is what he is doing he dont want to spend 7-9 thous on rebuilding trans and new tcm