My Gen I Prius is screeching at me with the BRAKE and ABS lights on, and I hear the electrically actuated pump pulsing as it tries to get pressure into the system. The pedal is spongy and will go all the way down, with the right amount of exerted pressure from my foot. I checked the pads and shoes, replaced the pads (worn 5mm down), shoes were as thick as new. The brake fluid level has never gone below minimum, and of course went up for FULL when I pushed the calipers back in for the new pads. I have not pulled the codes yet. Sometimes the buzzing and lights go off after 5 minutes and the noise stops. I have 165,000 on the car, and had the traction battery replaced at 143,000, so I am not looking forward to another big bill for ABS CPU or actuator assembly replacement. My battery did leak, and needed replacement, but the brake system has shown no leaks, but the pedal has gotten spongier to the point of the system coming on and yelling at me. Any similar experiences? Thanks, M&M
I have had no similiar experiences however, spongy pedal usually equals the brakes need to be bled. Unfortunately, the regenerative braking system is more complex than a simple hydraulic system. I would say you definitely need to get the codes to hopefully narrow it down to the regen or hydraulic portion of the system.
I have just finished going through HELL with my Gen1 Prius and braking systems issues... All signs were pointing towards the Accumulator / pump / booster... replaced all of them at least once, then at the very end, my non-dealer, hybrid specific shop noticed that a check valve was sticking in the Brake Master Cyclinder! A $150 part! However, to fix, they did have to take off the inverter, so I got some new coolant in the inverter cooling system. All in all, I spent about $4000 between the dealer mis diagnosing it, and the non-dealer repair shop (Mighty Auto Pro in Medina, Oh) in used parts / new parts / and the labor to rip everything out and put it all back in a few times each.
Thanks, I don't want to go the same avenue you did...that is why I am trying to figure it out without the dealer.....I think mine might be similar...and I hate the idea of having to remove the inverter to get to the brake booster and master cylinder. The BRAKE + ABS lights and the buzzer in the cabin have stopped for now, and I think I can do the brake bleeding and see if that improves the sponginess.
I've also had BRAKE and ABS lights with a shrill alarm intermittently the last two weeks. Took it to the dealer, and they found a code (1251 I think) that meant booster pump failure. Dealer got a booster pump defective reading once, but could not reproduce alarm. The tech said that the booster pump would have to be replaced ($1600), and then if that didn't work then the computer would be next. Sounds the same as one as one of the other stories!
It's very difficult in these cars to do ANYTHING without removing something else for access. If a little coolant has to be replaced in the process (plus labor), it's a relatively small price to pay, IMO.
Exactly same thing. Ditto. Brakes still work fine but it screams, pulses, and alarms for 5 minutes. They said I need a brake booster didn’t mention accentuator. Not many available. Weren’t any when it was in the shop so had to leave unfixed. My car also has 165,000 and just replaced the hybrid. Crazy weird
What trouble codes do you have? (To be honest, we never really know if one thing is "exactly same thing" as another until we have those.) If you don't have a scan tool that can read them, you can get trouble codes from the brake system with nothing more than a short piece of wire: Blink (a/k/a Flash) Codes – How to. | PriusChat Different generations of Prius had their brake systems divvied up into different numbers of components, as shown in this post. (That post is six years old, so the prices in it are bogus, and could have gone down or up, but it's still good for knowing what the different parts are in your generation.) Gen 1 was unique in having a master cylinder rebuild kit available, not just whole replacement master cylinders.
