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Your problem is definitely in the master cylinder area. Possibly the booster. Could you take and post a pic of the unit? There are several different versions of this system. I'd have to do a bit of research monday, but I'm pretty sure the correct (and very pricey) fix is to replace the whole unit.
Attached are photos of my unit. I don't think the booster can be replaced separately. I contacted my mechanic and he said if i already bled the rear brakes with the car on to activate the ABS and the pedals are still soft. I would need to bring it to the dealer to use the scanner on the ABS. Is there any home method to bleed the ABS module?
No home method as far as I know. There is also no need for a scanner to bleed the system. Nice try though dealership guy. I have the same system on mine and bled the entire car without using my scanner. If you bled it correctly following the procedure I outlined earlier, then bleeding is not the problem. Air in the system would not cause the symptoms you describe anyway. A failing ABS unit is possible, as well as a failing booster or accumulator. Either way, it should all be replaced as an assembly. Maybe your mechanic knows something I don't, but I doubt it. If he's willing to do it for nothing, then why not. Can't hurt. I wouldn't pay for that service though.
Think about it this way. You bled the brakes because you were having a brake issue right? You stated there are no fluid leaks right? How did the air get there? Even if you did bleed it wrong, the problem was present before you did that. Again, if its air, how did it get there? It doesn't happen unless you have a leak and ran low on fluid. If those 2 things didn't happen, then there's no air.
Thanks Gdwench, you been much help. I figure it must be the entire assembly. Even if there is air present, the pedal should stiffen up while the car is off.
I've been getting the handbrake light lighting up recently. There's no sound or any other warning lights as someone has had.
When I pump the brake pedal with the engine OFF there's noticeable resistant but after 10+ times it goes all the way down to the floor and there's little to none resistant.
I checked the brake fluid level and it was on the MIN level with engine ON so I filled it up to MAX. I did this last week (wednesday) and the light showed up again yesterday morning (monday).
Local Toyota dealer/shop said it's most propably the brake master cylinder that leaks but they couldn't find out where exactly. They refilled the reservoir but I don't know how much the fluid had been sunken over these past days.
They quoted me a price of 2170€ ($2400+) + labor for the new unit. Obviously I'm not gonna pay that much for it. If I can't get it fixed much cheaper I'll propably just leave it be and refill the reservoir as it sunks ... or take it to a junkyard..
Has anybody disassembled the BMC unit? On the explosion pic there are some seals but can they be changed?
10-25-15, 09:27 AM
Obviously I'm not gonna pay that much for it. If I can't get it fixed much cheaper I'll propably just leave it be and refill the reservoir as it sunks ... or take it to a junkyard.. 
