This is from today, its about 30*F outside and the truck was almost at operating temperature...

 

Lets start from the beginning: Is it slow to crank frist time run in the day? Does it take too long to start? Headlights, are they dimm with no other load? How bad do they dim with rpms up with a load (heater) applied. After running the enginr, place your hand over th wires, are they hot? Is the corrosion aroiund the ends? Just trying to trouble shoot the wires and batteries.

 

just had the same issue except i kept driving it. it boild the passengers side batt. come to find out it was a bad conection some where in the system causing the computer to think that the batt was low and over charge it. cleaned all the batt treminals and grounds and all better now.. just a thought