Had some bad luck on 2013 GMC Terrain. Took it to a mechanic to have the engine changed (2.4 66k miles inhaling oil) and I couldn't get it to start before I took it to him but it cranked. It started until I changed the throttle body and I didn't know the re-learn procedure. I go to him after he gets the new motor in and he says it won't crank. He is under the Terrain by the starter and says he can't find where a wire goes but he thinks it is on the starter. Said he put it there and nothing happens but he can jump power to the starter and it will turn over. I go home and get a schematic and it is the main ground wire for my ECM and TCM. I go back and tell the mechanic and he says putting a ground on hot shouldn't matter, but a hot on ground would? I have no check engine flash now and I checked it over yesterday pretty good (5 hours) and can't find any burnt wires or anything wrong but I believe the damage is already done. Would you agree that putting the ground on the constant starter hot would burn up the ECM and TCM since it is applying direct hot to the unfused side of these? I think I am going to have to take this to the dealer and I don't think it is going to be a cheap fix.