Very odd brake problem after being rear-ended

Recently my 2002 Tundra was rear-ended while stopped in freeway traffic. Enough that it totaled the Honda Ridgeline behind me and pushed my rear bumper down at nearly a 60 deg angle. Braking after the accident seems perfectly fine, except for one thing....when I press the brake petal (this can be at any speed, or stopped, or in any gear or RPM.....there is now a slight whining or humming. Best as I can describe is it sounds like the motors turning on EV cars and not like a vacuum leak. Noticeable in the cab, but no overly loud. You need the windows up but there's no mistaking the sound is present. It did not do this pre-accident. I'm the original owner and never have had many problems with this truck. Also, there's no ABS light or other lights on, etc, and the engine runs fine just as always. Again, brakes/engine/transmission function as they always have, with the exception of this whining sound. Thoughts on what is causing this? Thx

 

The ABS can be noisy without the light coming on. Check everything on the rear axle. The lines, sensors and for giggles check the drive line and the carrier bearing

 

Have you not taken it in for a repair estimate? Seems like it would the responsibility of the driver that ran into you.

 

The Tundra may be totaled based on repair costs, but it's easily driveable now and still is. Other than the back bumper damage, it looks likes like a run-of-the-mill 22 year old truck. If it's determined to be totaled, I plan to keep it and fix the issues myself. Considering the repairs, the brake whine is the only thing I'm not wrapping my head around.

 

Could just be shit that got knocked loose and is in the pads?

 

Nope. Does it whether wheels are rotating or not.

 

Maybe put your head down there and push the pedal with your hand while looking and listening.

 

I'd guess a popped brake booster diaphragm. If you were stopped in traffic and rear ended, sometimes the force of the accident can cause you to slam your foot through the brake pedal and bottom out or over extend the brake booster diaphragm, causing it to leak when you apply the brake. It's typically a small hiss until you put the brake pedal to the floor and it changes pitch. I had an old bronco that I did that to; replaced the brake booster and it was golden. Well, as golden as crummy 70's 1/2 ton ford brakes could be. So more like poo-brown-golden...

 

I plan on isolating the booster by plugging the vacuum line at the booster. Would assume that if the noise goes away, it's booster related; if noise still there will look into the ABS unit.