Slow battery drain with key off

[Lee A.]

I own a 99 Surburban 2500

 

I have had a slow battery drain that has been difficult to diagnose. I beleive this to be part of the reason for the short battery life seen in this vehicle. I have replaced the battery several times but had the battery to weak to start many times. If the vehicle sits for several days the battery won't start the vehicle.

 

I have had to jump start the vehicle several times and one of the repairmen told me that this may have damaged the onboard computer. My answer is that the problem existed before I jump started the vehicle, not because of it.

 

When I separate the ground from the battery and put my amp meter in line I have a .22 amp draw. Pulling fuse #2 to the transfer case the draw drops to .01 which is probably the clock and computer. With the fuse out the electronic 4wd shifter will have both the low 4 and the 2 high lights on. (For reference the interior lights have a 3-4 amp draw.)

 

Several different repairmen have given me several different answers, but the problem persists.

 

Is this a normal current draw for this vehicle?

 

Is it a possible feed back from another problem than the transfer case and transmission?

 

Where should I look to try to find the source of the current draw?

 

Is it a possible computer problem?

 

Has jump starting the vehicle caused problems to my on board computer?

 

I can hear a relay clic under the steering wheel when I pull and replace the #2 fuse. Is this relay a possible current draw?

 

Where do I start? Even the dealer is puzzled.

 

THANK YOU FOR YOUR HELP - Lee

[GM-Tech]

A 220 milliamp draw (.22 amps) is excessive, but on a vehicle driven regularly, it *may* not be a problem. Specs call for around 25 milliamps maximum draw.

 

Jump starting the vehicle should not cause a computer problem unless you accidently (even momentarily) reversed the polarity, i.e. positve to negative and vice versa.

 

Keep in mind that simply disconnecting the battery cable to hook in your meter can cause whatever is staying on, if it's relay controlled or something along those lines, to shut down. Then you put your meter in place and don't really see much of a problem.

 

We have a special cable we use that allows us to start the vehicle, run all the accessories, drive it, whatever. Then we shut everything off, attach the meter and only then, break the connection to the battery. This way, we never shut off power to components that might be active. Also note that you should leave the meter in place for a half hour or so to make sure any modules that are awake will transition into their sleep mode so you can get a true current drain reading. If you just hook up and read it, the current draw may be high but can go down after a short time.