I'm having same tuk sound from my front breaks. They are especially loud if I'm in applying breaks in reverse. I've taken it to Toyota Garden and Toyota Ravi almost 5 times. Once I paid for break service and 4 times they did it under warranty.
But the sound keeps coming back.
According to Toyota, it's a clip which displaces and grease dries up! They always say it's not a major issue, but when u spend 2mil; you expect a perfect ride.
You can get break service under warranty, but the problem keeps coming back and 2hrs wasted from your workday!
Not a happy customer.