Brakes - '08 Prius

rpolo

No brake fluid pressure to right rear wheel cylinder on a 08 Prius. Also abs, vsc and brake system warning lights are on. All started after installing new rear brake shoes.

thecardoc3

You need a scan tool to apply, and when servicing bleed the rear brakes on a Prius. Only the ABS computer can actually apply the rear brakes. In the event of a system failure you would have manual front brakes only.

rpolo

The left rear brake has pressure and works fine

thecardoc3

How are you making this assessment?

rpolo

Brake on left side is working when foot brake is applied. Right side does not. wheel cylinder is ok, no pressure when I open bleeder valve. Disconnected brake line, fluid will drip out but does not squirt out when foot brake is applied. I can't believe there is a blockage somewhere. What do u think?

thecardoc3

What I wrote the first time. The computer is responsible for putting fluid to the rear wheels. With any problem like this on these cars, right now you need a scan too that can access the ABS system and command the automated bleeding routine. With these cars you really CANNOT judge pedal feel and bleed the brakes like any other because the "master cylinder" is usually just an input to the ABS brakes module which measures the pedal force and position and communicates to the invertor assembly to command the regenerative braking and the ABS controller applies the rears just enough to keep the car balanced. Now when you come to a complete stop the system applies the manual service brakes at all four wheels but that is a single moment in normal operation and again the ABS controller does that, not the driver with the brake pedal.

In a full scan tool with this situation a tech has to perform all three bleeding sequences because again you cannot feel any air in these like a normal brake system. What is worse is that any air in the system above the front calipers cannot be bled without a scan tool.

rpolo

Thank you very much for sharing this information. It was very helpful. It is becoming difficult for the average guy doing his own work.