Newbie question -- periodic buzzing sound?

[houndrunner]

Howdy folks, and apologies in advance if this is either obvious or has been covered previously.

There's a periodic buzzing/whirring sound that seems to be coming from behind my dash -- almost like a small motor of some sort is opening/closing something. Doesn't seem to matter if the air is on or not, which is what I initially thought it was. Nothing bad appears to be happening, it's just this strangely specific noise that the truck decides to make at regular intervals. If I have music going or any significant AC or heat, I don't hear the noise either, so it's not super loud. Is anyone out there familiar with what I'm talking about?

(If I get really ambitious, I'll record a video of the sound, but I wanted to try my luck here first.)

 

[snivilous]

Electronic brake booster building pressure.

 

[hang10]

The Hamster wheel that powers these beasts, needs a little grease.....:guitar3:

 

[TXRick]

Can you hear it when the vehicle is off? Coming from under the hood? Might be your vacuum box or buzz box...

 

[Yukon4Runner]

Electronic brake booster building pressure.

Agreed, as an owner of a 3rd gen, it's likely the brake booster building pressure.

Buuuut, it could be something else making the buzzing sound...maybe something left in the glove compartment that vibrates...like an electric toothbrush, a hair clipper, a phone set on vibrate, or a,....now what else vibrates and buzzes...hmmmm

 

[ThorInc]

Agreed, as an owner of a 3rd gen, it's likely the brake booster building pressure.

Buuuut, it could be something else making the buzzing sound...maybe something left in the glove compartment that vibrates...like an electric toothbrush, a hair clipper, a phone set on vibrate, or a,....now what else vibrates and buzzes...hmmmm

Pocket Rocket...........

 

[billyboy15]

Its the power steering pump im pretty sure

 

[AgeOfOctane]

If it's a '96 and you can hear it after you turn off the engine, I'm with TXRick, the vacuum box.

 

[HawkNation]

I just ran into a similar issue on my '00 limited... Couldn't exactly tell where it was coming from however. It ended up being the rear HVAC fan, controlled on the backside of the center console near the floor. Maybe a stupid answer, but that's what mine was.

 

[bwarren]

If it's a 1996 it's definitely the vacuum box, especially if it does it only when it's hot.

 

[miguestner]

I'm with TXRick, the vacuum box.

 

[TorqueOfTheDevil]

Some people have reported a buzzing/rattling from the heater matrix valve.

 

[RustyMaine Yotas]

My 99 did the same thing until I replaced the stock radio with a aftermarket unit,
I also hear a very faint buzzing noise when I fire the rig up but I'm pretty sure it's the power antenna.

 

[Auce]

I had a buzzing sound forever coming from the dash, it wound up being the transfer case. If you lightly move the transfer case shifter left or right the buzzing stopped.