I recently bought a 2019 mk3 Jazz/Fit.
Over the past few days, I've noticed that when the hill assist releases the break, it causes a loud squeaking sound.
my breaks make almost no sound when using them while driving, so i don't know what could be causing it, or even if its something i should be worried about.
Anyone have any ideas?

 

That's not normal. My 2019 EX MT6 doesn't make any weird noise when Hill Assist does its thing. To be clear, it does make A NOISE when it releases, but it's just a short "voop." No squeaks.

Come to think of it, I've no idea how it works. Is it using the same mechanism as Honda Sensing (Automatic Emergency Braking / Adaptive Cruise Control), or something completely separate?? These Fits have manual hand brake (thank God!), so it can't be using parking brake related function....

I guess LX/Sport MT6 without Honda Sensing still has Hill Assist? That would mean there's a separate mechanism for it. Some sort of solenoid? Something rusted and binding?

 

"Sensors inform the brake-system ECU when the vehicle is stopped on a grade. The ECU maintains brake-line pressure for a brief moment while the driver moves their foot from the brake pedal to the accelerator pedal."
From Honda Info Center

 

k..im no expert. but the "ABS" system needs to be able to release AND build pressure.so it MAY be something the do with the abs system where all the brake lines run into..once again...no expert...not used to ABS...old person..but the motor that builds ABS pressure may be the squeaker .but if that's your ONLY problem and no check engine lights, live with it or use the handbrake...i use the handbrake cause i cant for the life of me get used to hillstart , my wife drives the car mostly, and she doesn't even know it has it !! lol...and she cant drive automatic!!. too different..lolX2!!

 

Improper operation of braking system would be my bet. Check for dirt/buildup on calipers/drums; slide pins, shims,etc. For calipers check to make sure pistons are compressible. You may have a collapsed brake line as well. This would be noticeable buy unmatched pad wear when compared to your other side. Brake fluid change out on these is every 2 years by what I recall, you'd be surprised how many issues come from something as simple as not changing it out every now and again.