GM is known for many common problems among a lot of cars. One of them is the side terminal batteries manufactured by AC Delco. In short they leak, leak, leak. When this happens the contact to the battery cables is severed but not usually before it leaks into the cable several inches and requires replacing both parts.
You will need an 8mm box end wrench, the longer the better to check. After unscrewing the bolt, remove the red insulator for the positive terminal. There, you will probably find a lot of whitish green powder; that is the corrosion. With a wire brush and baking soda w/water, clean it as much as possible. Allow a few minutes to dry.
To replace the battery, there is a 13mm bolt that holds a bottom lip to the ledge underneath it. Once this is removed the cross bar above the battery will have to be removed as well. I think the two near the front are 13mm and the one near the window under the cowl is a 15mm.
It's a tight fit, but can be done with a little patience. BTW use gloves when handling the battery and cleaning the terminals. Avoid eye, skin and clothing contact.
If this is the problem with your vehicle it should be performed before the alternator and starter are tested. Neither f those systems can be tested effectively unless the battery and cables are in good working order.
If neither of the solutions fits your situation, please post back and we can continue diagnosing.
Wednesday, November 18th, 2009 AT 6:54 PM