Autobreak/Anti Collision brakes grinding sound

[WanderingMonkey]

Hey all 

So while reversing into a car park space at work there is a main road on the opposite side of the pavement so naturally the car thinks a car is coming from left and right...

It triggers the anti collision a few times and the car brakes hard 

But during the breaking there is a grinding noise sounds like when you shift in a manual and grind a gear etc with a bit of vibration.

Is this normal? 

[Cyker]

Yeah that's normal. If you've ever braked hard enough to trigger ABS, it's a very similar sensation (Sortof you're suddenly driving over gravel with a pneumatic drill).

The new cars are all brake by wire, and when they autobrake I assume they're engaging maximum braking force which also triggers ABS, resulting in that horrible noise!

[TonyHSD]

It also could be from the electric brake booster which makes similar to abs pump noises while operating normally, same noise is present when opening drivers door or when push button to start the car. 

[Cyker]

I know the noise they mean because I've heard it many times  

It's very very disconcerting because it sounds like something very expensive has just snapped and is now grinding all sorts of critical gear teeth off, but thankfully it's just the auto-brake system. I'd really like to know how it makes the noise so disturbing (It's bad enough when you trigger it when braking hard but it's so much worse when the auto-brake activates!), but I'm 99% sure it's something to do with the ABS pump.

It's like a mix of the ratchet sound from a dozen handbrake at the same time with a sortof ominous creak, followed by an innocuous bong. Scared the  out of me the first time it happened...!    

 

[AisinW]

Fortunately, newer car warn us loudly when the handbrake engage. corolla now only have parking brake motor. I remember my colleague cannot stop his car because he drove with parking brake on for 8 miles. Either the brake fluid was boiling or rotor and pads overheating.

I always do hard brake test to test the ABS system when buying a used car.  It is loud, cracking and jerking. That's normal.

[Cyker]

One of the few good things about EPBs is they will generally unscrew if you try to drive off with them engaged. Does mean you can't do handbrake turns with them 'tho