Group,
I have searched and searched but have yet to find a post with this issue. I have the all awesome '05 V10 limited excursion. For the last 1 1/2 yrs I have been dealing with a constant battery drain. I have been dealing with it by disconnecting the battery after parking it. If I know I am going to drive it the next day, I can leave it connected but if it is going to sit for more than a full day it has to be disconnected or I will have a dead battery. We have done a power/ drainage check with a voltage meter by pulling all the fuses 1 at a time and nothing, I have actually done this twice with two different people to make sure it was done correctly. We found no difference with any fuses pulled either time. One time I ran into this older mechanic who said he knew exactly what the problem was and that it had to do with the 3 rear door system and some sensor involved with them. When I went back to talk to him, of coarse he did not work there anymore and I was back to square one. I am hoping someone/ anyone has heard of or unfortunately has had to deal with this same problem and can give some MUCH needed advice.

 

 

or any other after market lights, etc? Those are always the ones that got me in trouble.

If there aren't any aftermarket items, then I'm at a loss if you tested the draw correctly.

 

All light and everything shut off in vehicle. There is nothing aftermarket in the vehicle.

 

Testing system voltage at rest can be helpful, but amperage draw is more informative for detecting parasitic drain. Most DVMs have an amperage scale.

That detail aside, what IS the static voltage draw with everything connected? Did you wait the requisite amount of time for the GEM to stop providing aux power before you began your test?

How exactly did you do the test?

What was the voltage at the battery with it disconnected?

What was the voltage at the battery with it connected, engine off?

What was the system voltage when running down the road?

Where are you geographically, what is your climate?

What else happened about a year and a half ago that preceeded the drain showing up?

 

pull the batteries, charge them up and let them sit for a few days and check their charge then?

 

I just recently went through a similar situation where the battery would drain overnight. Since I was in the middle of doing the suspension, I decided to put it off until I was done. While under the truck, I found a ground strap rotted in half (under passenger front floorboard, from frame to body). I replaced the ground, since I was working under that section of the truck anyway (because honestly, if I didn't do it then, I'd forget). Lo and behold, the battery quit draining overnight. Did the 40-ish minute ammeter test to verify everything was good, and it was. Been fine ever since.

 

How many amps are being drawn?

 

Keep in mind when testing that it takes around 40 minutes for everything to "go to sleep" on these things. If you are searching for a parasitic drain and you take your ammeter measurement minutes after you shut it off, you will not be working with realistic measurements. I think mine took right at 38 minutes for everything to go to sleep- that means the meter was in series the entire time with me not waking anything up (like opening the door to make the domes come on). you need this "bedded down" measurement before you really do much else, to see if the "overnight" draw is excessive or not. There will always be a tiny parasitic draw due to memory functions (radio, PCM, clock)- so you will never see a total zero.

 

I was having a similar problem. I would lose enough voltage, that after 2 days the truck wouldn't start. It ended up being the alternator.
On the test stand the alt was putting out 13 volts. On the truck, it was only putting out 12.1. Also, the alternator was warm to the touch all the time. Put new one on, now putting out 13.8 volts, and is cold to the touch after sitting. Truck can now sit a week without a problem.

 

Thank you for all the information. I am going to do the 0 min test and give back the readings afterwards to see where we go from there.

 

OK, all cards on the table I am not mechanically inclined at all. So all the information I get from here I will be passing along to my mechanic buddies so they can help me LOL. I am hoping this forum will help me to get to know my vehicle better and allow me to do smaller projects to it. Now with that being said, I have no clue what a ground strap is but I can look it up or ask a friend.

 

A ground strap is simply a webbing of wire, usually without a coating, with a ring on each end to secure it with a bolt. Think about the old-school lawn chairs that used plastic webbing material- a ground strap looks like a miniature version, but with strands of wire instead of plastic. On my 2000, if you look under your vehicle (passenger side, right under the floorboard), there is one with one end bolted to the frame and the other end screwed to the metal of the body. I believe that strap was in that location for all years, but I could be wrong.

The reason for ground straps is that the body is electrically separated from the frame by rubber bushings (the engine is too), but everything grounded has to make it's way back to the negative post of the battery. Since the rubber bushings prevent this from happening, ground straps are provided to facilitate that path.

 

Ground strap.