2008 Expedition intermittent electrical leak
 

Hey folks I am new to this forum, but have gleaned some useful info from here before so I thought I would try and contribute and ask for help at the same time.

As the title implies, I got a voltage drain -sometimes. Usually it does not drain the battery overnight, but it has, and if it sits two days there is a good chance it will drain it. I have been living with this issue for a couple of months, and finally last week I got off my ass and decided to do some troubleshooting.

I installed a blade switch on the ground terminal, and disabled the passenger side door closed switch so I could get to the fuse box.

Attachment 148891

So for a couple of days I got no leakage -reading 20mA or so. Then last Wednesday -400mA after more than an hour of sitting, computer should be off for sure.

I start plucking fuses, while the wife checks the DVM. First fuse I try is the radio -it is fine. Then I start going through the fuses starting at number 1. On fuse 5, the DVM does not drop when I pull it but jumps up to 800mA when I put it back in. According to the owners manual this is the fuse for " Keypad illumination, 3rd row seat enable, Brake Shift Interlock (BSI), SPDJB" After a bit it drops back down to .4A and we continue on. I also get the same reaction from another fuse, but I can't recall which one right now, but it was around 23. I check all of the fuses even the ones under the hood and I never see the voltage drop to zero on the DVM after unplugging a fuse. I also pulled all the relays under the hood as well -nothing. By now though, I suspect I have awoken the computer the DVM has dropped to 300mA from the original 400mA.

We go back inside, and I come out about an hour later and check, it is still 300mA. I disconnect the positive terminal to the alternator and boom, I get 0 volts. So this past Saturday, I replace the alternator with a new one. The truck has sat for a couple of days so it won't start. I put the charger on and go inside for a shower, come back out and realize I just cooked my battery. I had the charger set to 50Amp :'(

I put a fresh battery in and check it the next couple of days and all is well. Just as I start feeling pretty good about things...400mA again:-arrgh

I did not troubleshoot it then as I had family stuff to do, I just opened my blade switch so I would have full charge the next day.

My current guess is it might be starter.

Kelvin

Did you pull the fuse for the rear wiper? Very common parasitic drain.

So, today the truck has a drain, last couple of days it has been fine. It is pulling 400mA.

I disconnect the hot from the alternator, the current does not drop. I also disconnect the connector from the alternator with no drop in current.

Alternator not the problem.

Just as I am getting ready to remove the hot from the starter soleniod, my electrical engineer friend removes the lead from my DVM and reconnects is -basically disconnecting and reconnecting the battery. "...uhhh dude, I think I just reset the ECM". Anyway the current spikes to 700mA, and then drops to 400mA in less than a minute. So this makes me think maybe my drain is the ECM because I know it pulls around 400mA right after I park her and all the lights go out.

I eat lunch and go back out, now it is reading 200mA. For kicks I pull the fuse for the rear wiper -still pulling 200mA. Not ruling it out quite yet though -something may still be legitimately awake (I ate pretty quick). I am going out in another 30 minutes to check a few more things.

Okay I just checked, and after 30 more minutes it is still pulling 200mA. So I started pulling fuses:

Fuse 20: Adjustable pedals, Datalink -no change
Fuse 27: Ignition Switch -no change
Fuse 29: Instument Cluster -no change
Fuse 35: rear video camera -no change
Fuse 36: PATS transceiver -no change
Fuse 37: Climate control -no change
Fuse 38: Subwoofer/Amp -no change
Fuse 39: Radio -Spike to 700mA falls to 400mA within 10 seconds and sits there. I left the fuse out, and I will check in an hour.

Okay more than an hour, but...

with fuse 39 out the current is 200mA. So as far as I am concerned...

Fuse 39: no problem

I have to leave work, when I get home and after dinner I check and still have a 200mA draw. I check a few more fuses...

Fuse 42: Trailer tow battery charge coil -no change
Fuse 43: Rear wiper logic -no change
Fuse 45: Front wiper logic -no change
Fuse 46: Climate control, Auxiliary relay control -no change
Fuse 47: Power Windows -no change
Relay 48: Delayed Accessory Relay -no change

Fuse 32: Restraints control module -no change
Fuse 31: Compass, Automatic Dimming mirror -no change
Fuse 29: Instrument Panel Cluster -no change
Fuse 28: Radio -no change
Fuse 26: Instrument Panel Cluster -no change
Fuse 25: Demand lamps, Glovebox, Visor -no change
Fuse 24: Horn relay -no change
Fuse 23: High Beams -no change
Fuse 22: Park lamps relay -no change
Fuse 21: Fog lamps -no change
Fuse 17: Liftgate -no change

Fuse 25: Climate Control no change on fuse removal. When I put the fuse back current spikes to 900mA and then drops to 400mA in a few seconds. Need to wait until ECU rests...

Okay back down to a 200mA draw. I check fuses 1 through 14 in the passenger fuse panel, skip 5, because it is the drivers keypad, and I didn't want to wake up the computer again. I also skip 11 and 13 because they are spares.

I move on to the engine compartment fuse block...
relay 1: -no change
relay 3: -no change
fuse 4: -no change
fuse 5: -no change
fuse 6: DROPS TO 30mA!!!

Fuse 6 description is ABS (valves). Okay, now I am gonna have to do some research on this.