I have a 2002 Surbuban that the brand new battery dies when the truck is not started for 2 to 3 days. There are nothing that I can tell that is staying on when the truck is turned off.

 

Although its possible that the battery is a bad battery from the factory, you need to check for parasitic drain. Open the fuse box while the vehicle is off and use a test light or multimeter to check forpower on all the fuses. If you find a fuse with power on it, see what it goes to. That will narrow your search for the offending short.

 

Easy drain check: take a turn signal bulb, attatch a couple wires (or just use a test light) and disconect the negative cable. Put the light in between the cable and terminal. If it lights up, you have drain.

You may consider looking at the cables and conections as well. Rare on a newer truck, five years is plenty of time for corrosion to seep in and build up. It could be keeping your batery from getting a full charge.

 

Another thing to keep an eye on, make sure you're getting charge to the battery. I've replaced a couple of alternators on some of my GM's over the past decade. I'd look for the drain first though as suggested. If you don't find one I'd think about havingthe alternatorload tested.

 

This is referred to as " parasitic drain " , all modern vehicles will normally have a small amount of parasitic drain for the various electronic control modules and constant memory for things like stereos, etc.

The test for this :

With a Multimeter set to DC amps , without the key in the ignition, doors closed and everything OFF

1 - disconnect the Negative battery cable
2 - attach one lead from the meter to this negative cable
3 - attach the other meter lead to the negative battery point

wait a few minutes for the reading to settle ( this is for everything to re-initialize ) and observe the reading, which should be somewhere in the ball park of .010 (milliamp) to .020 (milliamp). [ 1 amp = 1000 milliamp and 1/2 amp = .500 amp or 500 milliamp ]
This will depend on what accessories your vehicle has.

If you find a high reading , for example .500 amps ( 500 milliamp ), you can do one of two things to locate which circuit is responsible for the high draw.

#1

- leave everything connected as mentioned above
- remove one fuse at a time and see if the reading drops significantly

just remember to shut the door or disable the interior lights so they aren't on.

#2
- reconnect the battery cable
- pull one fuse at a time
- place one lead of the meter on one terminal of the fuse socket
- place the other lead of the meter to the other terminal of the fuse socket
- observe and record the reading

This will direct you to which circuit has a problem.

 

Things that have happen to me in the past was a hood light staying on even when it was closed. I removed the fuse first then open the hood felt the bulb and noticed it was hot. And this was after the car was sitting overnight. I disconnected the hood light and it fixed that problem. I also had a old car that the glove box light would stay on even when you closed it. You might want to pull the glove box light and the hood light and see if that helps. Those are two drains that wouldn't be noticable.

Right now i have a problem with the factory CD changer on my silverado. When I put copied cds or CDs that are scratched up, the changer keeps trying to read them even though the ignition is turned off. That would be enough to kill my battery after a few days. I have to take out the cds if Iam not driving the truck for a while.

You can get a solarpowered battery charger that sits on top of your dash. This helps keep the battery charged when your truck sits for a while. It kept me from having a dead truck until I found the battery drain. I think I paid under 20 bucks for it. Hope this helps

 

On 2000 Tahoe good battery would drain in a few days. Checked parasitic draw which was 700ma. Traced draw to a door lock problem, after exercising all door locks the draw dropped down to 70ma. Fuse involved also fed the cig. lighters. Removing and replacing the fuse #13 you could hear the selinoid in the door click. Problem very confusing as car could be fine for many months if driven enough to keep battery charged but then after a couple of days of being parked, dead battery. The parasitic draw was intermittent due to use of the door locks.