I have a 2012 F250 model X2A I bought new in Dec of 2011, its the 6.7 Diesel.

I have this buzzing sound emitting from it sometimes for days after being driven. The noise is inconsequent, it may occur from a few minutes to hours to days after the vehicle has been shut down. It will sound several times. This has been going on since the truck was new.

Its not the DEF pump.

It sounds like the relay that turns the lights off, such as the interior, or under the hood light etc. But, I'm not sure if it is coming from this relay or not. It does not seem to be as loud as the lights relay.

I have had it to the dealer but they can not find anything wrong. My garage is very quiet and the buzzing sound is not very audible. The dealers work stations are pretty noisy so I'm not surprised they can't hear it. The service manager even took it for a ride and parked it at what he said was a quiet area and listened to it for ten minutes, nothing.

Has anyone else experienced this?

I would like to find out if this is normal or not. I really don't want to have this causing a fire and burning my house down.

It would help to know where at in the truck the buzzing is coming from.

Buzzing sound.

As near as I can tell its coming from under the hood. The problem is when it does sound its only for about a second, so you can't really track the sound to its source very easy.