Buzzing noise under dash when car is off

[Deb Cy]

I have a 2017 Explorer and just had the dealer put a new battery in. After opening and closing and leaving some doors open over the weekend while camping and also having the aux on to charge my phone (something I do all the time) my battery was dead, and I mean really dead, had to charge it for quite some time to get it running again. I figured I just used it too much in aux mode without having started it for a couple days. Today I got in my car to clean it out and there is a buzzing noise coming from the dash, a humming and maybe even a light clicking noise. The key is no where near the car, nothing is on. I sat in the car a while with all the doors closed, made sure all the lights were off, disconnected the phone charger and still the buzzing. I turned the car on, made sure all the fans were off and the radio and turned it off and still a buzzing. This must be what drained my battery but I cannot for the life of me figure out what it is! Any ideas?

 

[peterk9]

Welcome to the Forum Deb.
Maybe a bee got in when you had the doors open on your camping trip.
I really have no idea what the noise could be. Also, I would think that having the doors opening and shutting and the accessory mode ON likely did the battery no favour. The Battery Saver program will turn the interior lights OFF after 10 minutes but then when a door is opened again, the countdown starts again.
Did you leave the vehicle sitting undisturbed for at least 8 hours after the new battery was installed?
See posts #2 and #5 in this thread; Battery Replacement / Upgrade - Battery Re-Learn

Peter

 

[Deb Cy]

The dealer put the battery in, it definitely didn't sit 8 hours right then and there but it did that night. I don't even think I needed a new battery, I got the oil changed and they tell you all the things you should stay on top of and they said the battery was bad. Well the car is under warranty so when I brought it back I told them to replace the battery at which point they said they tested it and it was fine. Well that seemed a little shady to me so I told them too bad, you said I needed a battery so you need to replace it. Anyway, for sure the opening and closing it with the lights being on over and over again didn't help, I assumed that was the reason for the dead battery so I really wasn't too worried about it. But my car has been parked on my driveway since yesterday, not driven or turned on at all and something is definitely "running".

 

[peterk9]

You could try disconnecting the negative battery cable for a few minutes before reconnecting it. With it disconnected you shouldn't hear that noise. By using this method be aware that EVERYTHING in the vehicle loses power and anything that requires voltage to maintain data will reset to factory build status (such as the transmission learn, etc). Perhaps this will reset whatever is causing the noise but it is difficult to say since the cause is unknown.
Is it loud enough so that you can hear it with the vehicle turned ON?

Peter

 

[Deb Cy]

You could try disconnecting the negative battery cable for a few minutes before reconnecting it. With it disconnected you shouldn't hear that noise. By using this method be aware that EVERYTHING in the vehicle loses power and anything that requires voltage to maintain data will reset to factory build status (such as the transmission learn, etc). Perhaps this will reset whatever is causing the noise but it is difficult to say since the cause is unknown.
Is it loud enough so that you can hear it with the vehicle turned ON?

Peter

It is not loud at all, more like a low buzz like you would hear from one of those long shop lights. I turned the car on for a minute to make sure that everything was turned off just in case and I didn't hear it with the car running. But it was still there when I turned it off again. I would imagine that the noise would go away if I disconnect the battery but I'm not really sure that would help me figure out where it is coming from. I'll take it over the dealer tomorrow and ask, it is still under a bumper to bumper warranty. Just a pain the behind because who has time for that non sense. You just don't expet this kind of stuff on a car you buy brand new =(

 

[613GT500]

The Explorers have an intelligent battery monitoring system, which should prevent parasitic draws.
The buzzing noise can be related to the power inverter, in which there is a TSB for it.

 

[Bobs2018ExplorerSport]

I had my Optima battery in my 2015 Edge Sport fail miserably, and even after I jumpstarted it and ran it (thinking it was recharging the battery), further testing showed it was still mostly dead... and yet, I also had the same weird buzzing coming from the dash area. Turned out what little charge was left in this dying battery was trying to keep various memory options going, but it was too low, so the buzzing happened. Seems that the battery was still putting out about 8-9 volts, but had absolutely no current/amperage behind it, so it was a goner. Putting in a brand-new battery instantly solved the problem after that!

 

[peterk9]

Do you have any update on the issue Deb?

Peter

 

[jrcallaway]

I’m having what seems to be the exact same issue, except it is intermittent. I have a 2018 Ford Explorer. Sometimes when I turn off the vehicle I hear a faint buzzing sound coming from under the hood. It definitely sounds electrical and not mechanical like a fan. If the buzzing occurs and I don’t restart the vehicle then the battery gets drained over a period of time and then I can’t start it again without a jump. However sometimes when I shut off the car no issue. I’ve tried a number of different ways to shut off the vehicle including with and without the parking brake depressed. Also tried to turn off automatic lights, radio, climate control, emergency brake, pretty much everything I could think of. I can’t consistently re-create the issue and the dealership is saying that they can’t help if they can’t diagnose the problem. I have a brand new battery around 6 weeks old.

 

[peterk9]

Welcome to the Forum.
Have you tried opening the hood when the buzzing sound is there to see if you can tell where it's coming from?

Peter