07 Classic LBZ CC battery killer
 

I'm usually in the old truck section, but i need some help on a new truck, Anyone out there got some GMC knowledge? I'm a pretty bright guy, and usually can locate a problam and fix it. But this has got me stumped.

I have a 07 classic, with the LBZ Dmax. The thing is killing batterys in the last week. Usually in the fall, it will pull this if it sits for a couple days, but this is a kill good batts in 3 hours type thing. I have unhooked everything foreign to the truck, plow set up wires, my FD radio, etc etc.

Removed the neg cables from both batts, used a test light to see if there is a draw. There is a Huge one. The fuse block under the hood is the culprit, but we removed every fuse, maxi fuse, relay, still nothing.

We've looked for broken wires, i've pulled the block almost completely apart, i found one 50amp fuse that dims the test light, but not much, unplugged everything i could find under the dash, pulled all the dash fuses. I'm stumped, going on 3 hours now, and i've called everyone i know.

Anyone got any thoughts. I haven't started unplugging computers i guess what will be next.

Thanks
Glen

Re: 07 Classic LBZ CC battery killer
 

The Test light trick dont work on these newer trucks.

1. Select the highest amp scale on
an ammeter and disconnect the battery negative cable.

2. Install the ammeter between the battery and the battery cable. A jumper wire needs to be connected in parallel to the ammeter to reconnect the battery at the same time the meter remains installed. Both the ammeter and a jumper wire are connecting the battery cable to the battery at this time. This allows the vehicle to power down (go to sleep).

3. Wait 30 minutes. Turn the ammeter on. Remove the jumper wire, being sure that the ammeter does not come disconnected. This is now the actual vehicle's battery drain.

4. Once the amount of the drain has been recorded, remove the fuses one at a time to locate the source of the drain. Leave the fuses out until draw is isolated, as reinstalling may reset timers and give a false draw.

Re: 07 Classic LBZ CC battery killer
 

have you had the alternator tested? bad diodes will cause a key off drain

Re: 07 Classic LBZ CC battery killer
 

Lol yea im a retard sometimes, I found out the test light trick Doesnt work the hard way, I did the amp draw, found I had a 6amp steady draw. Something was on.So started pulling fuses, found that the MBEC fuse was the draw, and after a search I found it was the power seats. The pass side switch was jambed hard back. Once I moved it, it snapped back. I pulled the fuse just to make sure, but I'm hoping this is it. I don't want to jump it again in the rain.
Thank you very much for the help.
Glen
Posted via Mobile Device