Vibration when applying brakes

Hell TW, seeking advice.
I recently returned from a trip to the Sierra. While there I noticed a vibration started when I applied the brake pedal. The vibration occurs about 3/4 of the distance as I push the brake pedal. It's a subtle vibration on the pedal but is definitely noticeable and annoying. I also noticed what sounds like a small electric motor turning on under the hood that lasts for 3-4 seconds when I apply the brakes. I never felt this vibration prior to this trip which is weird. Once I returned I immediately checked out TW to see if this was a common problem. Sounds like a few people have experienced this. Has something to do with the Hydraulic Brake Booster Pump. But why did it start all of a sudden? My truck only has 4K miles on it. If the truck is off, key out of the ignition and I pump the brake, the sound and vibration does not happen. If I turn the key to the on position (car running or not) and pump the brake, it happens. When driving, It happens just about every time I pump the brakes. The attached photo is the component that turns on. Is that the brake booster? It doesn't seam normal to me. Any suggestions or ideas on the cause? I'm taking the truck to the dealership in a couple of days but honestly I don't trust dealerships. It's a 2014 OR DCSB and is still under warranty.

 

This sounds like the normal offroad brakes. They are different from the other tacoma models. The brakes feel a bit more touchy and will create a bit of a pulsing in the brake pedal. When I had an offroad it did the same thing.

You can always take it in if you feel they aren't functioning correctly.

 

Never noticed that. Do all 4x4 tacoma's have that?

 

Chris,
Thank you for the response. This vibration is definitely related to the part (see picture in first post) that kicks on when I apply the brakes. I don't know what that part is. I don't understand why it just started happening at 4K miles. It's not a pulsing feel. I feel the vibration coming from that device through the brake pedal. Brakes work fine though.

 

I'm not sure why it just started, but the offroad I had would do the same thing. It would make a sound similar to the abs, and at the same time i could feel it in the brake pedal. I don't remember if mine had that cylindrical container or not.