Need help from GMC owers or Auto Mech

[Lakesport90]

I have a 2001 GMC with 5.8 ltr engine. The truck runs fine, when its running.
If I leave it sit up for 2 or 3 days the battery is dead, I mean dead, no lites, horns, etc. I brought the old battery in for a test and they said it was bad,-' OKay, truck runs fine for a month and the same thing happens. Bring battery back to see if I just happened to get a bad battery. Shop tells me this battery is bad, gives me a new one. 5 days later same same thing. I checked lights, raido, ets made sure nothing was on. Only thing different is the Radio will not shut off when I open the door, I have to turn it off. I am the only one who drives the truck.
Any Ideas?

Thanks

[BasinDawg]

OK so we do have an issue if the radio is not turning off...It does not see an open circuit when the door is opened. Does the dome light stay on?
Do you have availability to an ammeter....You need to check for a load on the system once the door and everything is off

[BasinDawg]

If you open the passenger door will the radio turn off.... Even after you have opened the door will the window"s" still operate (assuming you have power windows)

[Lakesport90]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by BasinDawg &raquo;</td></tr><tr><td class="quote">OK so we do have an issue if the radio is not turning off...It does not see an open circuit when the door is opened. Does the dome light stay on?
Do you have availability to an ammeter....You need to check for a load on the system once the door and everything is off</td></tr></table>

Dome light goes off, I'll have to check to see if radio goes off when passenger door closes.

[JOHN202]

If it's something beyond what you can see, give this a try.

http://www.popularmechanics.co...rains

[BasinDawg]

Thats a good link to what I was saying...Hopefully he has an ammeter if not you can rent one for free from Auto Zone.....Or buy a decent on for 15.00 at Harbor Freight

[Lakesport90]

Thanks guys, I have an ampmeter, I will try trouble shooting, but what ever it is
its killing the new battery where it won't hold a charge. In fact my charge says I have a bad cell now.

I keep looking.

[BasinDawg]

that sounds like your output of voltage from your alternator is too high....check to see what the meter reads