Originally Posted by rlandes
Ok guys, here is my dilemma. I have a 2003 Gmc sierra 1500hd 6.0
Every morning I wake up she is as dead as a doornail. I have a battery that tests fine, I just installed a heavy duty alternator. I have a brake booster, and plow attachments. I have taken them both off individually and noticed no difference. I seem to not be getting a draw from any self added attachments. I can jump the vehicle in the morning, let it run for 20 or so and then shut it off. In an hour or so she is dead again. Any leads would be so appreciated its unbelievable as my stress level is flying high and my truck is in huge demand. Thanks in advance.
Start with the simple and disconnect the battery, if the battery still goes dead. Then the battery has a short in one of it's cell cause it to go dead and the battery will need to be replaced. The battery is dead in an hour would also tell me that it's going to be a pretty heavy load that is causing your battery to go dead so it wont be like a radio or glove box light left on.
Start with disconnecting the battery and keep us posted.