[Scion owner]

I have a 2009 scion tc manual trans. My brake pedal intermittently sinks to the floor. There are no fluid leaks we installed a new master cylinder and bled the brake system twice. And STILL the brake pedal randomly will sink to the floor.
what else could be causing this to happen??

 

[Dallasrhi]

You could have a brake caliper leaking. I blew out a caliper and replaced it, but when I did I couldn't get a pedal and has weak brakes so the car would struggle stopping. I eventually had to replace the master cylinder also and that helped my issue out. It's possible that the brake booster could be going out but I don't know of anyways to test them.

 

[merdone]

Maybe there's still air in the lines somewhere.

 

[stainless]

hello everyone. i have a 2010 Scion tc and the identical problem, brake pedel intermittently go all the way down, no braking power.
I am on the 3rd master cylinder, the abs computer module has been replaced and the problem still persists. every mechanic refers to the MC as the problem. Bleed with every repair. I suspect the front passenger brake may be the cause, or a faulty wire harness. I really dont know. Please help!