I have a new to me 2006 Chevy 3500 with a duramax that after 3 days with out driving it the batteries will be dead. Old batteries it happened and with with new good batteries it has happened also, If you have had this happen or know how to troubleshoot it I would appreciate some guidance and no arm chair quarterbacking.
Thanks Scott

Have the alternator checked. We had one that did it randomly. A pull your hair out kind of problem. Does it have an aftermarket auto start? They can give grief sometimes. Hope that helps.

No aftermarket auto start.

camper shell?

Unhook a battery cable and put an ammeter in the line with the key OFF. If it shows power going through it, start pulling fuses 1 at a time until it goes away.
It's possible that it's designed to keep something running full time. One thing that can draw power when it's off is a security system. Or maybe an underhood light that isn't shutting off.

Try pulling the fuse to the radio, that was the problem in my 06 LBZ.

Thank you all keep them coming gotta get this figured out
No canopy

Check the alternator and voltage regulator. It might not be properly recharging the battery so starting it a few times is pulling it down and leaving it there.

This! Don’t use a cheap amp meter.

Also the fuse trays are known to go bad and cause parasitic drain. Had that on an 08 Suburban. New fuse tray, no more problems.

I've removed the the fuses in my Tahoe for; power door locks, heated seats & mirrors. Unplugged the underhood light, & lighted passenger vanity mirror. Removed the dome light & glove box bulbs. Checked the alternator myself with a good digital VOM & even had an auto electric shop load test it. It was driving me nuts.

I've seen many lighted vanity mirrors on the passenger side of all brands of vehicles, but didn't know this over optioned damn thing had one on the driver side as well. I'd never used the sun visor, & the cover was closed on the mirror with the light on.

Before I found the additional lighted mirror, I installed an inline, remote control power disconnect I found on Ebay. It has a key fob just like the power door lock one. Sold as an anti-theft device, which is an adder, but another way to halt battery drain.

My ‘05 did the same. Parasitic battery drain. It was an intermittent problem and never got it diagnosed. Put a battery disconnect switch on the floorboard in front of the seat. Turned it off and on ea time. It was a work truck with 350,000 miles on it so not an issue that the clock was never correct.

Bud had an 06 that would go dead every once in a blue moon, swapped alternators and problem went away.


Last fall my 06 left me dead on 2 instances. I was going to swap batteries and when I took the cables loose there was a ton of corrosion between cable and battery. I cleaned em up, put new terminal bolts in the cable ends, greased em up good and have had no issues since.