ABS, Brake and Traction lights on with codes C1252, C1253, C1256, C1365

I will pass the information along. We assumed that it wasn't getting power in some fashion because we unplugged the new brake assembly w/ master cylinder and plugged back in the old one to see if maybe the part was defective and it didn't click/respond in any way. He said would of heard it at least buzz.

 

Well, the buzzing sound is made by the motor, so the motor fuses would affect that. Of course fuses are dead simple to check, shouldn't need to tell a mechanic how to do that.

How about other signs of the unit receiving power, other than power to the motor? Do any of its three lights on the dash light up? Does it appear in a scan tool's list of responding ECUs?

 

So it was only that 30/30/40 amp he wasn't sure if maybe there was something we couldn't see at a quick glance and was causing the issue. We were doing this in my driveway and just didn't have a mechanic shop to quickly assess certain things. Turns out... it was the 12v after all. We picked up a new 12v and fuses to diagnose and got back to it today and sure enough when we opened the door to the prius, we heard the pump click. That said, we determined the 12v must be dying. Needless to say, halfway through the bleed cycle and it went out. A quick swap allowed us to finish the job. So yeah, a bad 12v will throw everything out of whack, but thankfully now all the lights and beeping have gone away and the car is fully operational without incident.

 

Have you checked your accumulator voltage using scan tool? HVe you Heard or seen any signs of leakage of fluid or air under dash at brake pedAl I just worked on accumulator not too long ago... I just went after accumulator not both units ...I heard and saw leakage tho at master cylinder. Used live data to find the culprit...

 

The sssshh-ssshhh indicates gas bubbles in the system that it would be worthwhile to bleed out. Removing the bubbles reduces the amount of brake fluid that has to be moved on every use of the brake, and that should increase the brake uses between runs of the pump.

Excessive gas bubbles in the system may also, I've speculated, contribute to a rare but bad situation where the system's fail-safe mode ... isn't.

 

So all was fine for a week but just earlier the abs lights and beeping all started again. I noticed my brake fluid was near empty just now? Should I be able to see fluid and could that possibly be the culprit?

 

If you are assuming because you do not have a scan tool ready at hand, you should be able to get the codes anyway, like this:

Blink (a/k/a Flash) Codes – How to. | PriusChat

Then you don't have to assume.

Replacing the components will require a scan tool that is capable of stepping the brake computer through the fluid bleed process. I believe most scan tools that can do that can also call up the other calibration procedures that may be needed. There are only a few, and I believe the one for the linear solenoid offset is done automatically as part of the long-form bleed procedure anyway.

 

I know this is an old post but I wonder if your mechanic needs to reprogram after replacing the brake master cylinder (which has the control module) since the parts are different. My current part is 47210-47310 and the new one number 47050-47140? thanks.

 

The actuators do have different firmware for different cars (and trims; it's different for 15" than for 17" tires), and there are different part numbers for the ones that come from the factory loaded with the different firmware variants.

For all I know, it might be possible to turn one into another just by flashing the corresponding firmware on it, but I'm not positive that's a thing people do. (If it is, I can picture some extra confusion cropping up downstream....)