As mentioned in another post, daughter called me saying that all of the sudden all the dash lights were coming on and the low beams kept flashing on and off randomly. I limped her home and immediately checked voltage at the battery and it showed 14.1v. Waited overnight to start testing the next day. Checked voltage of the battery before starting and 7v and no starty.

So jumped it off to have the battery and alternator tested, and the guy at the parts store said we have a parasitic draw on the system.

Before I start the process of pulling fuses and testing amp draws, I wanted to check if this rang a bell with anyone?

 

@cybercop do you have an ODB dongle ? If so remove it, you will still have to check draw before and after but my old one stop sleeping and was pulling a enough to kill a battery in a week of sitting.

 

In fact I do. Didn't even think of that.

 

Seems like a pretty substantial drain overnight... Still have air shocks in the rear that might be leaking? Having the compressor pump them up overnight can certainly kill a battery. Mine had been swapped to coils but would still kill the battery overnight until I reprogrammed the ECU.

 

Nope, all on springs. I do have two windows acting up, but never remember a windows motor ever causing this issue.

 

So I ran some test with a multimeter set on 10A and looking at DC A readings. (I hope that makes sense)

When I had my ODB reader plugged in, I was getting a reading of .36 after everything settled down. When I removed it, I would get .31 after everything settled down. So a bit of a draw, but what was causing the rest.

After a lot of testing, I finally found that F11 (ABS) caused my reading to go from .31 to .01. What is really weird, once I put the fuse back in, it did not go up to .31 until I opened a door on the truck ( I guess activating the BCM, not sure how that would activate the ABS). I would then have to once again have to remove F11 to get the draw down to .01

So a couple of questions. Is .31 3.1 millliamps? If so, is that enough to cause a impactful drain?
If so, why would my ABS causing a drain? I did make a mod to the ABS system to get rid of the 3 Amigos.

 

Negative, that would be 310 milliamps.

The .05a for your OBD dongle is not a problem. That's likely just enough to run the little LED on it.

The additional .3a.... That's still a really minimal draw. Alternator will not cause your battery to die overnight unless there's a short inside it. Only causes issues while running. You need to have your battery tested. It sounds like your battery capacity is getting low. I leave a cooler running in my vehicle overnight that draws a fair bit more than that. I want to say 8a or so, but I don't recall off hand.

 

Its a recently purchased DieHard Platinum. But I guess it could still be the battery.

 

Having an issue with mine, drawing 600-1000ma on the battery lead to the under hood fuse box. I pulled every relay and fuse in that box without any change. Guess I'll get back at it in the daylight.
As I work through fixing leaks and such it just sits for weeks at a time. Usually with this draw it takes about a week for the battery to be dead.

 

I measure that too, ECU & BCU draw that much when ignition is off. When you lock the doors via the remote the current consumption goes down after several minutes, since these units are put into sleep mode. Just tamper the hood switch with a clamp, lock the doors and come back half an hour later. Current draw should be down significantly to several milliamps.