'04 Chevy Truck Draining Battery

I have a customer with a battery drain problem.. Dealer said it was the alarm (of course) and I checked it out. Showed no problem. He took it back to the dealer and told them (and showed) them no current draw heavy enough to drain it over night (I turned the engine off around 8:30 last night, shut the door and at 7:50am this morning, dead, without the alarm on) They told him that it was a problem with the onstar and that there is a recall on it.. it's been draining the battery. Ok, 1. Has anyone else heard about this. And 2. Anyone else have a problem with battery draining in the newer Chevy GMC Caddie truck and SUV? If so, maybe this is the culprit. George Bratcher David's Car Stereo Baton Rouge, Louisiana

With the battery protection on that vehicle there is nothing that should be able to drain the battery completely over night. The only thing that would disable the battery protection would be something tieing into power on a computer controlled timed wire such as a domelight, if the computer sees a draw on one of these wires then the computer will never shut off. Do you know the specific draw?Certified Security Specialist

Always check info with a digital multimeter.

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First off you need to find out what the draw is and trace it from there. If the draw is over 25 milliamps then you have a parasitic draw. It is very easy to find a draw but for some reason they make it difficult. Use a dmm that has a current function and put it in between the negative cable and the battery. It takes a minute for the computer to go to sleep and show the real draw. I doubt the onstar is the problem as I work on gm's all day and have never heard of a problem. If the problem did not start until the alarm was installed I would guess it was something you did or defective product. It is very easy to diagnose. Get your meter out and check what the draw is. DanDan

I had that same problem on my 03 tahoe.  It ended up being my mistake of using the domelight as a door trigger wire for the alarm, which caused the computer to never shut off as auex said...(It was actually one of his posts a while back that helped my figure out the drain!!) I ended up using the grey/black in the drivers door, the BLACK/ white in the pass door & the blue/black and GREEN/ black off the back plug of the bcm under the dash for my 4 door triggers. You also have to diode isolate each wire before it ties into the brain of your alarm.

Did anyone read that the dealer said that this was an ONSTAR problem??? Problem is fixed.. I was just wondering if anyone else has heard of this.. that's it.. It wasn't the alarm. It's been in for 8 months now, it jsut started. I know how to check current draw also.

It is not the domelight staying on that drains the battery, it is the fact that the car's computer doesn't shut off. I used to deal with this all the time. If this wasn't the case then why did my company pay anywhere from 800 to 3000 dollars a pop, this used to happen alot, to the dealerships that wasted so much time diagnosing this. European vehicles have the same problems.Certified Security Specialist

Always check info with a digital multimeter.

I promise to be good.

Tell Darwin I sent you.

I've been sick lately, sorry I won't be on much.

I wasn't trying to be a smartass. I was simply stating that a dealer said that there has been a recall on the OnStar and that it's staying on and draining the battery and if anyone else has had this problem with a customer, whether it's is an alarm, stereo, radar detector, phone, Nav, this may be the problem. Period end.