I have a 08 GMC Sierra with a 5.3L. It is 1 yr old this week with 3500 miles. Now the problem. Last month, after sitting for a week, the battery was dead. I charged the battery and took it to the dealer the next day. The dealer checked the battery, said it was okay but there was a parasitic draw that he couldn't find. He wanted to keep it for a day or two but I didn't have the time. A couple days later I took it to a different dealer and told him the whole story. 2 hours later, he said we replaced the battery, it was sulfated. I asked about the parasitic draw and he said it was 31 milla-amps which is within specs. Everything was great until this morning (Monday) when the battery was dead again. I drove it Sat. and everything was fine. It's going to the dealer again tomorrow but I would appreciate any ideas.

Thanks,Jim

 

that sounds more like a ground problem if it keeps killing batteries, check the frame side ground for the battery make sure its tight and see if its completely clean of paint and other garbage that might work its way in there then throw some connection grease on top of it to protect against the elements and put some on your batterey too. also open the caps on the battery make sure you got electrolytes in it, if not you can get battery water from a parts house, dont use distilled or tap water it wont hold a charge as long.