Battery Drain

Stelzner66 · April 23, 2016

I have a 2008 GMC Sierra 1500. Its a pretty basic truck, there aren't really any extras on it. First a little history of the truck; its a salvage truck, the original radio was stolen out of it. The person I bought it from told me that when he bought it the original radio was stolen out of it, he bought a replacement radio that was from a similar GMC truck. The dealership had to unlock the radio due to the original was stolen. This is when the drain started happening. What I have done so far to try and figure out what is causing this problem is first, I took it to my mechanic and he figured out where the draw was coming from, he said it was the radio, so we took out the 15 amp fuse for the radio, that took the draw down significantly, but still a draw. Next, I decided to take the head unit out and took a voltage meter and plugged into each individual wire, the accessory wire (dark green) had a draw on it of about 2-2.5 volts, and it didn't matter if the engine was on or off, the key on power was shorted to the constant. This is as far as I've taken it. I have considered that maybe its something with computer causing it to draw (since the radio had to be unlocked for it to work) or have considered that there is a short somewhere on the accessory wire. So as of now, the fuse is out and the head unit is not installed, The longest it has sat without being started was 4 days and I had to jump it, but more recently it has sat for 12 hours and was dead, that only seems to happen about every 8 days or so. most days it starts up every morning. Any suggestion or thoughts would help. Thanks!

Wires · May 1, 2016

First I'd ensure the battery is fine. My 2008 had a POS battery right from new (if I left it a week in the garage, the battery was stone dead).

There was a recall/repogramming done due to the BSM (I think that was the case) where it wouldn't turn off, and would drain the battery. You should check to see if you unit is effected by that.

If that is all fine, they I'd hook an ammeter on between the positive battery terminal and the lead from the battery (inline). When you first connect it, the BSM, ECM, etc will draw a lot of power (amps) and then drop down to zero after a couple of minutes.

If you still see a noticeable draw (more than 100-200 milliamps), then start pulling fuses until it goes away. That should point to the smoking gun.

My guess is it's just one of the first two though. If the battery is OEM, it's probably bad.

Stelzner66 · May 2, 2016

Thanks for the info! I will give this a try when I'm able too.

backyarder1 · May 2, 2016

If you don't use Onstar, you can take the onstar fuse out. My battery kept draining, too, and when I took that out, it didn't drain as quickly.

txab · May 2, 2016

If you don't use Onstar, you can take the onstar fuse out. My battery kept draining, too, and when I took that out, it didn't drain as quickly.

That's because on your '04 Onstar had a problem. Originally Onstar was analog based. In about 2007 when Onstar went digital they eventually phased out support for older vehicles. One problem was the vehicles still would try to "phone home" to communicate regularly with home base as they were programmed to do, even if you didn't have a subscription. Since Onstar home base wouldn't answer (digital vs analog) The vehicle just kept trying and trying until it would eventually drain the battery, depending on how much you drove it. A letter was sent out to vehicles owners letting them know to bring their vehicles in and they would disconnect the Onstar unit to resolve this issue, free of charge

HagiborChayil · May 5, 2016

Can also try a true parasitic drain test with a multimeter. It is time consuming but since the radio seems to be at fault I would look into an aftermarket radio aand use either the idata link maestro or pac rp5-gm31 harness. Those are designed to integrate properly and I have ever noticed drain with either of them.

carkhz316 · May 11, 2016

Agreed with others here, in confirming how much of a drain you have. Nominally, it should be less than 100 millamps (.100 Amps), but realistically, it shouldn't be much more than 50 milliamps. I would double check the radio by unplugging the radio itself while monitoring the draw. If it drops to an acceptable level of current draw, then I would ditch the radio.

kaufmankdk · May 19, 2016

I eventually tracked my problem down to a "headlight / dome light switch". problem solved. It was intermittent and I chased it for the past 4 years.

carkhz316 · May 21, 2016

Glad to hear you got it solved!

Stelzner66 · September 7, 2016

Update- I installed a kill switch and mounted under the steering wheel. I put the radio back in so I could use it. I was turning the kill switch on/off every time I drove the truck. I've had the kill switch in for about a week. Everything was working good. But today, I went to start the truck and it barely started. While I was driving I watched my volt meter and it started out at about 14.5. As I was driving, only a few miles to the gas station, the meter dropped down to about 9-10. While I was gasing up I left the switch on. It was on for maybe 4 minutes. Went to start it back up, and nothing, just a clicking sound. I got a jump and while driving home, the meter read 14ish the whole way, only a few miles. Got home, shut the truck off, turned the killswitch to off, went out about 2 hours later to test it with a meter. This is what it registered. Keep in mind I did this back to back in this sequence.

12.3 killswitch off

10.2 killswitch on/ truck off

9.9 killswitch on/ Key on/ truck off

10.2 killswitch on/ truck off

10.4 killswitch off/ truck off

The truck didn't start. I was thinking it might be the alternator starting to go? The killswitch I bought should be able to handle the load.

When I was mounting the killswitch, I had the switch off, one of the posts on the switch made contact with piece of metal and was able to complete,the circuit; I know this because the dash/dome lights came on for a second. I wrapped the metal with electric tape, and covered the posts on the switch with tape as well. This seemed to fix that. I played around with tonight to make sure that wasn't the problem. I don't think that was it. I'm planning checking the battery throughout the night and recording the voltage. What do you guys think about this? Thanks!