Urgent Help!!! Braking problem with Prius 2010

that's your vsc kicking in because it detects the loose pavement and thinks you're slipping. just press harder on the brakes. there was a software flash to make it a little less noticeable. it's usually worst around 6 mph when the car is transitioning back and forth from regen to brake pads.

 

Any warning lights?

 

I had a similar problem with my 2008 Prius.

It turned out that the brake caliper pins were dry and hence brake pads were not engaging properly. Cleaning and lubricating the caliper pins solved the problem for me.

 

vsc = vehicle stability control

 

We've had the brakes go into "fail safe" mode, first sensation is partial loss of brakes. But there's also a batch of brake lights, and sometimes "check hybrid system" warning.

Still, might be something similar. The brakes work, but they're less responsive, hard to describe.

 

don't know about japanese models, is it in your manual? i think when you pres the power button, the vsc letters should light up for a second, while the car does it's self check.

 

sorry, i'm a dummy when it comes to japanese. no idea what it would look like. you should try some experimentation on the rough roads when it's quiet, so you can get a feel for what is going on, when not in a panic situation. we have a lot of people complaining about this on gravely roads.

 

You say that you've just bought the car - do you know if it's been undriven for a while? Maybe there is a build up of rust on the disks or, as mentioned above, on the caliper pins.

Have you applied the brakes hard on a good road to see if they work correctly - it has ABS, and it may feel a little unusual braking hard if you're not used to ABS intervention.

 

vsc with skid marks is correct. you can remove rotor rust by putting the car in neutral on a quiet road around 30mph, and gently applying the brakes.

 

I took to dealership, they hooked up to Techstream and reset the system, dismissed codes, car then behaves normally. They're not sure of the cause, but latest time, they thought it might be my Scangauge being hooked up, but not sure. I'm trying driving without ScanGauge, so far no issues.

Still, if you're not getting warning lights, not sure, maybe applicable.

 

i had that too. it was caused by OBD2 reader plugged in. There was malfunction lamp and regen braking was turned off. the code was U..... , loss of communication, forgot the exact number. i restarted the car without the reader and everything was well.

the OP clearly has a different problem. sounds like the loss of braking issue prius was recalled in 2010. maybe the foreign markets didn't get the recall?

 

If I'm reading this thread right, all the OP seems to be talking about is the same thing Priuses have always done, my 2001 does it. I bought it in 2008 and, thanks to PriusChat, I had already read about it and knew what to expect before I experienced it the first time. (In fact, based on what I read on PriusChat, I took my car out on a rough road and made it happen, to get used to the feeling so it wouldn't startle me in normal driving. Eight years later it still happens under the right conditions on the right road surfaces, and it still doesn't startle me.)

The Prius has two entirely different ways of braking, one by repurposing the electric motor as a generator, and the other a normal brake system at all four wheels. The regen braking can only use the two front wheels, which could be a problem with poor road traction. So any time it detects any sign of traction problems, it gives up on the regen braking and goes straight to the hydraulic system, with which it has control of all four wheels.

The switch isn't perfectly seamless though, the regen braking is already cut off (remember, the car was worried about traction) and it takes a split second to bring the hydraulic brakes into full action. During that split second, you are not slowing at the same rate you wanted. No matter how it may feel, the car has not literally decided to go faster ... it's just a momentary drop in the rate of braking. (To the seat of your pants, there's no way to tell a "reduced rate of braking" from "forward acceleration" from a change from downhill to uphill ... with your eyes closed they'd all feel the same.)

All that said, even though this has been a long known Prius quirk since the earliest models, there were reports that the original 2010 software had a longer transition time that bothered more people, and so Toyota had an update for that model. It doesn't make the whole transition moment go away or make the car not a Prius, but reportedly it makes the transition time shorter, probably more like the earlier models. So you could check whether that update has been done.

-Chap