1999 LX470 strange noise behind dash

[ffl3883]

Hello,

I have a 1999 LX470, 140k miles. I noticed there is strange noise (sounds like servo motor or some kind of !Removed! sound). when I first turn the key to light up the dash also when I press brake several times. It also happens frequently during driving when I press brake pedal. Brake still functions. Here is a YouTube link. 1999 LX470 Noise Behind Dash 

you might need to put on headphone to hear the noise clearly in the YouTube video. Just wondering what the problem is . Any thoughts and gauidance are appreciated. 

Regards

Felix