Lexus-Toyota-Scion Technician

OEM belts should work fine. If you are replacing the any pulleys for gains I can appreciate that otherwise, you can repaint them (just make sure the crankshaft pulley has it's mark for TDC) I would recommend replacing the both idler pulleys, timing belt, thermostat, water pump, tensioner, and the accessory belt. Also, you will need 3 o-rings (for the water pump, the thermostat, and one large one for the inlet pipe (I believe)), the water pump gasket, and FIPG for the thermostat housing to water pump.

So I replaced the pads and rotors. I put in drilled rotors and PBR pads that had 200 miles on them. The shims were re-used. I applied brake lube between the shims. The anti squeal springs in the rear were replaced along with the pins. When I replaced the brakes, I pushed the pistons back into the caliper but I didn't crack the bleeders open I have bled the brakes using a vac-ula, the scan tool, and manually (key on, assistant presses and holds pedal and waits for the actuator to build pressure). No air bubbles are coming out. I have tried bleeding 8 times or more. Here is the problem. With a steady application of the brake pedal, I have a firm pedal. Near the end of my braking action, the pedal travels farther and the ABS actuator buzzes and it feels like the brakes give out. I have two codes, C1223 and C1256. The first code is a generic code and the other is Low Pressure Accumulator...something. Basically a problem with either the accumulator, ABS motor, or the pressure switch. A Master Diagnostic Technician believes that the issue is a faulty master cylinder and so does another technician. A new master cylinder is $1869 with a brake booster. A used MC is $325. My question for you all is what do you think might be the problem? Has anyone run into this before?