brakes overheating?

My guess: You are trying to maintain a speed that is too fast and using too much manual braking.

You need to anticipate the downgrade and SLOW DOWN before cresting the hill.
Engaging B early won't hurt either.

Setting a speed about 5 mph BELOW what you think will be safe into the cruise control before cresting the hill should be good enough to prevent you from using much manual braking.
The cruise will try to prevent it from going too fast.......and it usually does a remarkably good job.

 

I don't think there should ever be a 'grinding' noise. And I trust that, as a veteran PiP driver, you're familiar with the sound the engine makes when it is helping you brake, and you wouldn't be calling that a 'grinding' noise. Right?

If there's really a grinding noise, are you able to make it happen in other circumstances? Like braking on a flat road? Like braking on a flat road after shifting to N?

If there is a grinding noise and you can reproduce it in other circumstances like that, I would definitely have someone look at the physical brakes.

 

i would have the brakes inspected. there's no rubber to burn, something else is going on

 

It should still be under warranty, right?

 

Yes indeed. They may already be damaged......due to an initial defect or due to improper use.

 

AND tell them what you told us.

Please note that there is NO warranty on brake wear, regardless of the cause.
Most often they just want to replace EVERYTHING and charge you for all the work.......because there is no warranty on brake wear.

I wish you luck. Some of these cases get really nasty.

 

At 30k (or 3 years, whichever comes first) Toyota USA maintenance schedule recommends a more in-depth brake inspection.

You can confirm by having a read through the the warranty and maintenance booklet. If it’s missing you can download PDF version, Toyota Tech Info is one source.

 

How is the batteey level. I noticed when driving on a steep downhill and the battery already fully charged car goes to b automatically. Car remains at b at least untill battery level goes down one bar . So not much to do but using the brakes. Sometimes have this issue too when roads are 6%or10% downhill but so far my rotors are ok , no pulsation.during those downhills , the car easily catches up a speed even if on b mode it gets to 90mph in seconds. Have to slow down to 40mph .b wont help much.

 

Uh, just NO! Wherever you are taking this car for service ... you "need," to go someplace else before you die! Something is seriously out of wack somewhere?? And there is no way in any fashion that you should be able to smell burning rubber?? If that is correct then something is seriously wrong with the brakes??

And just so you know on a long down hill straight w/o using much in the way of fuel our 2005 (smaller engine) will do 101 mph without breaking a sweat. And when I decided that well curve ahead and the speed limit will he 35 mph and "I do not want to go to jail for felony speeding in a Prius???" I softly applied the brakes. And there was no smell, no drama the car simply slowed down, as you would expect it to do.

Something is seriously off with your brakes?? Disk brakes in good condition "DO NOT," grind and the smell of rubber burning ... is not even in the realm of possibility?? Something is seriously off with your car, it should not be being this?? You can get, I do believe a free Brake Inspect at any local "Tire Store??"

"Something," is not right with your car? And if you have any car guy friend's ... put it up on jacks and pull the wheel's and go from there. Something is obviously wrong!

 

And what’s that free tire shop inspection worth, about what you paid for it. Seriously, Toyota recommends a tri-yearly or 30k mile inspection, you know, when the calipers are lifted off, everything inspected, cleaned and relubed.

don’t kid yourself, or others, that that just falls in your lap, for free.

 

Sigh ... "Discount Tire's 's, Les Schwab tires and Tires Plus all do free "Brake Inspection's." But hey if you want to play the "Game," take the car is and say "Check the Alignment ... I think it's off?? They will check the alignment and they will check the brakes "anyway. It's what they do.

On my car's it's 1.5 degrees negative front and 2 degree's negative rear on the 944's, I had them max out the caster on the 951 Turbo ... for high speed stability and well that was a mistake?? In America the max speed limit is not 140 +, the car was dead stable at that speed but it really did not like turning from dead straight ... lesson learned,

My 87 Toyota Mini Truck, the dealer could not do the alignment as it was set up for Canyon Running and it was to low for there ramp. The Pt Cruiser of course with a modded suspension. Tires Plus ticked me and my wife off (because she was the one taking it back,) Lowered off course camber kit so 1.5 degrees negative and of course the steering wheel should be centered at 12:00, not 12:15 or 12:10 or 12:05 ... !2:00 do get it right or do it over until you do! After three attempt's they got it right!

But my point is a "Tire Shop" will check the Brakes for free.But perhaps the secrecy to a free brake check is to ask for a free alignment check??

But the point is, there is something obviously wrong with the Brakes on the OP's car! And I would speculate it's most likely the front brakes?? But "we," can't see the car?? And that dealer seem's to have only "Tool's," at hand checking out car's?? Going down hill, this car is not safe?? And I am pretty sure the typical Prius Driver, is not interested in seeing how fast the Digital Display will keep tracking track past 101 mph??

I don't have a dog in this fight but I can say, that a much older Prius at triple digit speed's "does not do this," something is wrong??

 

The car doesn't automatically go into B mode, unless Toyota made a significant change from prior generations.

From D, it will fill up the battery and then start mild or moderate engine braking by spinning up the engine RPM. The increased engine noise will be noticeable. But without cruise control engaged, this is far short of the RPM and degree of engine braking and increased engine noise that happens when you manually shift it to B mode.

 

The automatic "B" mode may be something the newer Prius's do?? I use it once now. Once I understood it, I down shift for corner's. But this Wednesday on my downhill Run back home, I will suck it up and set the CC for 55 mph and report back.

 

Numerous owners of previous generations have incorrectly described the D mode full-battery engine braking as "automatic B mode". It does use the same tools as B, but the degree and strength are very different.

B mode "downshifting" for corners is energy inefficient compared to simply using the brake pedal, and provides no real benefit. It doesn't get you what downshifting a manual transmission gets in that situation.

If it works similar to prior generations, then CC will produce much stronger engine braking than what you were doing in D.

 

Point Taken.

"Energy Inefficient??" LOL, I will grant that for hyper milers?? You are most likely correct?? But in the real world I have gone from 4300 Carson City to 5000 ft, Moundhouse NV and then a 101 mph downhill blast back to Dayton NV (with a downhill slope at 101 mph) and averaged 51 mpg.

B mode does not scrub off as much speed as a manual transmission, true enough granted.
But B mode in a "Prius," properly utilized allows you to use that to scrub off a little speed and use the a light application of brakes to transfer weight and preserve momentum. You don't need much in the way of Horse power downhill, if your not constantly scrubbing off speed. Exhibit A:

But those tires are only good for maybe 10'000 mile's, the sway bar's are stiff and spring and shock's have to be insane?? That car rides like crap! Aside from the tires my 92 Tercel is there! A monster if the road has curves and sucks bad the rest of the time! My wife hated that car. And if he has a significant other that is not a car girl, she doesn't drive that car.

But a "Prius," that can beat a Viper down Mulholland Drive ? Nuff said, that's one and there will be more.

Well CC was off for me. I mean seriously who hit's CC at 101 mph in America?? But before the corner at the bottom I did hit "B" and lightly applied the brakes back down to 55 then 45 then 35 ... no noise, no drama, no big deal.

Something is seriously wrong with the OP"s car! It need's to be checked out by someone that has a clue! That car is not safe, especially for a 2019??? Just saying.

 

I wonder if this jailbird was using cruise control. Just happened last night.
Passenger dies after speeding car goes airborne, crashes into car dealership lot; Driver faces DUI charges

 

If the "hill" is really steep, 55 is too fast.

What is the % grade on the warning signs ?
What is the recommended speed for big trucks ??

You need to set the cruise to at least 5 MPH BELOW your desired max. speed because it won't control it completely.