For a while now, maybe 5 months i notice that my expedition humms when the car is not on... it does it even when there is no key in it or doors open ect... just humms...

i have no idea what that could be and up untill a few weeks ago it didnt overly concern me.

what did happen, was overnight my battery drained... it completely drained. So i went out and bought a new battery, a duralast red top with 750 CCA.

for about a week it was fine, would start up normally and everything was good...

i noticed that the humming sound that the vehicle makes got a bit louder with the new battery.


So... i figured something must be pulling from the battery when the car is off, and i'm not sure if the humming is related to it or not.

what i did was put a test light in between the neg terminal and the battery cable and it lit up when the car was off, door was closed ect... so now i knew for sure that there was something draining the battery. I pulled each fuse in the vehicle and in the engine bay one at a time, and the test light still stays on...

so does anyone have a clue what might be wrong with my expedition.

any suggestions/help is appreciated.

 

I believe your next move to continue your test light proceedure would be to disconnect the alternator.
AL.

 

its definately not the charging system... the alternator is in good working order, it recharges the battery when the engine is on.... i'm 100 percent sure its not the alternator.

 

OK, in the past I have the same problem with my Exp 99 but with no humm sound. I did a similar test just like you did, but :
- Did you pull out every fuse in both boxes, the Passenger compartment fuse panel and the power distribution box located in the engine compartment, to see which one causes the bulb to light?
- Did you wait at least 10 minutes to make sure the delay accesory relay to shut down itself?
After this test to be performed properly you should be able to determine the root cause. Hope this helps

 

i'm not really sure what that is...


yes, i went through the fuse panel in the cabin and the one in the engine bay.

and after pulling each fuse individually, the light still stays on... it got a little dimmer...

so that leads me to beleive that there is a short in the wiring between the battery and the fuse....



as of now, i'm just pulling the negative terminal when i park the truck.

 

I know you dont want to hear it but....Im pretty sure you truck is about to explode...Just kidding man. Can you hear the location of the hum? I know sounds can be tricky in the engine compartment as they resonate easily with all the metal. Maybe get it lifted up and listen beneath it. If you have a military friend and a base near by, they should have a hobby garage where you can access a lift for 3 bucks an hour. Something is discharging your battery at a very accelerated rate..especially if its audible.

 

the hum isnt constant... it happens once in a while, so i dont know if its the hum is whats draining the battery...

i do need to locate the hum and try and fix it... but i doesnt hum on command

 

The delay accesory keep the power to the windows and some other stuffs for 10 minutes after the ignition is off, so is likely to have the truck draining a little current just before the ignition is off.
There are just a few things that are power up just before fuse box, the starter relay, the starter motor, the cold start heater relay, the generator and the Bi–Fuel relay module. This last one is a good candidate, since if it fails, it will turn on the fuel pump, producing the humm noise you are hearing.

 

ok, i'll test out those things you mentioned...

could very well be that the relay has a short or something...

i'll let you guys know what happens.