My trucks acting up, if I run it towing, then shut it down, it wont restart, it acts like a dead battery but both are new, I have noticed that the volt meter is way down like the grid heater is stuck on and thats when it wont start after a few trys the volt meter will pop back up to 12 volts and it will start, the weird thing is it only does it after towing. looking for any clues why the grid heater would come on after the engine has been running