I have an 08 base Prius without stability control. My wife has an 07 with the works. I have never had the problem I'm going to outline in her car, and we have 15000 miles on hers, only 3000 on mine. In the past two weeks in the 08, I have noticed if I am coming to a stop and I hit some rough road, the traction control light comes on and the brakes, well they feel like the go out. I'm probably going from 30-35 mph before I brake. The rough road would be a pothole or really uneven pavement. I'm surprised the traction control is kicking in at all, but is it normal for the brakes to do that. I'm not slamming on the brakes, just putting even pressure on them to come to a stop. The first time it happened I wasn't sure what had happened, but it has happened 3 more times in the past week. When the traction control light goes off, the brakes then grip like they normally would. Like I said, this has never happened in the 07, which is why it worries me. I used to own an 02 Isuzu Rodeo that did the same thing and it had traction control too. It just doesn't seem normal. Any advice?
Sounds normal. Not sure why you haven't felt it on the '07, but you could test it out under similar conditions/speeds/road to be absolutely sure. What you're feeling is the transition from pure regen braking to friction braking. There's a mild decrease in braking force when regen kicks out requiring slightly more brake pedal input to get the same amount of braking force from the friction brakes. When you hit the bump the car's ABS/TRAC senses that as a potential loss of control situation and wants to switch you to emergency/friction braking.
Maybe the reason for the difference that you noted is because your wife's car is the Touring model, equipped with better tires? This is why some owners get rid of the Goodyear Integrity original equipment tires as soon as they can.
Your car has the same ABS brakes and traction control, so it will do the same thing under similar circumstances. I suspect it is just random luck, or perhaps different tires and suspension. Tom
Thanks for the replies. Makes me feel a little better to know that it was normal. I would bet the tires have something to do with it too. Thanks everyone.
I think I have said this before but mine never did that until I increased the tire pressure past 38PSI
