Brake pedal goes to floor with firm push

You left out a couple of critical details:
1) Did it do that before the repair was made ?
2) When you use the brakes during normal driving, does it seem to work OK ?

I suspect that the dealer is correct because.......BOTH of the Cs I have owned did that (3 including my daughter's).

I did not discover it until I was trying to test the "hill holding" feature.
Found out the the "hill hold lock" will only work if you actually are ON a significant hill but the pedal will always go to the floor, or very near to it, if you push hard enough when stopped.

The braking system does NOT have a direct connection between the pedal and the brake shoes......because of the ABS system.
It might even be "brake by wire" but I'm not sure about that.

 

Yea I would bleed it, the heck with what dealer says. I just take the cap off and pump brake slowly.. Some may spill but level will probably drop when air comes out, may have to add more...

Sad a dealer can't make as before and as every other car is.. Pretty lame to say it's normal when it's not.

Since doesn't do it driving all they care about is liability and extra money out of pocket since they are already paid their flat fee.

 

It is almost a lame as making pronouncements about a situation without actually knowing all the details.
Almost.

 

I have owned a 2004 and 2007 Prius and neither had the brake pedal travel to the floor. I would say that definitely is abnormal behavior.

If you decide to bleed the brake system you should use Mini VCI and refer to the repair documentation at techinfo.toyota.com for the procedure, because you need to exercise the various solenoids within the brake actuator assembly. However it is truly unfortunate that you feel the need to DIY here.

An alternater approach might be for you to contact another Toyota dealership service department for assistance, or call the Toyota Customer Experience Center.

 

BUT......did you ever try to push extra hard on the pedal while the car was stopped in traffic to actually SEE what would happen ??
Do you still have a Prius that you can try ??

I don't know about all models but I can say for pretty much certain that is is NOT ABNORMAL on the C models that I have owned.

And I am not sure that it really goes ALL the way to the floor board but it feels like it gets VERY close.

 

Yes, I tried this on the 2007 today. The pedal travels around 1-1/2". It reaches a firm stop. The behavior remains the same whether the Prius is IG-OFF or READY.

I don't own a Prius c and will not make any comment about that model's normal behavior.

 

OK so what is your perception of how close the pedal comes to the floor when pushed hard ??
(It is just a perception, after all, unless it actually hits the floor.)

 

Probably 3" above the floor.

 

I had some time to research this issue further in the factory repair manual. I hope the following snapshot will encourage the OP to pursue this issue with a competent Toyota dealer service department (which obviously means some other dealership than the one he went to recently.)

It is not obvious that the system needs to be bled, but certainly there is a braking system problem given his observation that the brake pedal will reach the floor. For example the brake master cylinder may have partially failed.

Further, the OP indicated he had paid $120 for a brake fluid flush. That was an unnecessary charge because the brake fluid should have been replaced as part of replacing the brake actuator pump. So in effect the dealer was paid by Toyota via the extended warranty, and also paid by the OP's credit card, to replace the brake fluid.

 

This is no doubt good advice.
But what do you suggest that he should do if the next dealer tells him the same thing ??

I still want to hear whether or not the pedal action is good (the same as before) in normal daily operation.

 

Tell the dealership service writer that the mechanic needs to do his job by researching the factory repair manual as needed to understand this issue.

 

On both my gen 3 and gen 4 the pedal travels all the way to the floor if you press down on it, and it has to. How else could the hill-hold assist work? It requires you to push the pedal all the way down(in my 2015 you even hear/feel a little click when at the bottom and that engages hill hold assist)

The brake pedal does not operate like a standard car. If you push it hard enough it will go all the way down. Not to the floor, but all the way down to the bottom of the pedal's travel ability. You will hit a hard stop.

I think this is what you are describing, I think the pedal is going to the normal 3 inches from the floor "at the pedal" maybe 1 inch at the lowest point on the pedal's joint.

 

I think if you do some more testing, you will find that the "hill assist" does NOT require that much pressure on the pedal.

First, you have to BE on a hill or else it won't work at all.
I presume that means enough of a grade so that the car actually rolls backwards inspite of the "creep" function of the transmission.

Then, once the car rolls back a bit if you let off the brake, another moderately firm push should engage the "hold"......but for only about 5 seconds I think.

 

On my 2010, the hill hold will engage on any grade, or flat ground (for grins, I just made a little trip where I used the hill hold at every stop). The key seems to be to make a second, distinct, firmer push on the brake pedal. It doesn't seem to need to be let off, or allowed to roll. It doesn't engage with a single push no matter how hard. But after sitting there stopped, holding the pedal, and then distinctly pushing it further down in a new motion, that seems to set it every time.

And (I never knew this till now), the time limit of a few seconds only applies after removing foot from brake. There's that much time to get from the brake to the go pedal. But as long as foot stays on brake, the light will keep blinking and hill hold stays engaged. My past uses of the feature always involved waiting to the last possible moment when the traffic light turned green, stabbing the brake down to engage the hill hold (because I thought I only had a few seconds) and then proceeding up the hill. Now I know I could just as easily set it as soon as I've stopped, and just let it blink the whole time.

I'm not sure what you mean here: the hill hold is a feature done in software in the skid ECU ... nothing needs to click (though the computer does supply a little beep). If you are hearing/feeling something clicklike at the bottom of your brake pedal travel, I'd be thinking more about a worn pedal bushing or something like that.

-Chap

 

My 2015 works like you describe, EXCEPT I can activate it on the first press of the brake by pressing it all the way down to the bottom until a hard stop, and then pressing a little harder and I will feel and hear a small click and then a beep and hill start assist is active with an icon on the dash. It's not quite a click, but you can tell there is a button beyond the pedals hard stop point that gets pressed. You can do it anywhere up or down hill/flat as long as you are in drive. This is how its been in any 2012-2015 Prius I've ever been in.

My 2017 does not work like that. The hill hold is automatic and it only works when you are on a hill and you don't have to press the pedal to the bottom, it is automatic. No indicator or beep when activated.

I liked the older system better because i used it for other things sometimes than just hills.


But ultimately I have never NOT been able to push a Prius brake pedal to the floor while sitting still, ever. They all do it if pressed hard enough. There is probably no problem with OPs car. While there is still a hydraulic link to the brakes from the pedal, it is only used in a failure situation. When you press on the brake pedal a sensor determines the hydraulic pressure and the computer determines what to do based on that.

If it senses small pressure at 50mph it will brake 100% with regen. If you hit them hard at that speed it will send 100% to the friction brakes.

If you are in park and not moving at all even if you press the pedal all the way in you are still only pressing against the sensor. If your electronic braking fails THEN the brake pedal will behave like a normal car, without power brakes at least, because you'll will be directly pressing the pads to the rotors.

 

Have you ever noticed this button on a parts diagram, the wiring diagram, or in the New Car Features Manual description of how the system works?

I'm sure you're feeling something, but you might be jumping to conclusions about what it is.

-Chap

 

There is only ONE vehicle type that I know of where the brake pedal is SUPPOSED TO sink while stopped at a light with even pedal pressure. They are the early PowerStorke equipped Ford E/F series and the reason is that the vacuum pump is belt driven and the system is NOT designed to maintain a constant pressure DIFFERENTIAL between atmospheric and vacuum sides of the diaphragm, as is the norm.

With a Gen2 Prius, the brake system is powered by electric motors that pressurize the brake fluid, which is then stored in accumulators. Brake pressure output should be directly proportional to pedal effort under all conditions.

As a side note, the OP should inform TMC that not only did TMC pay for brake fluid and the bleeding procedure under warranty, but that the offending STEALership charged the customer as well. Normally, an OEM would consider this activity warranty fraud. Finally, it is ILLEGAL to charge a customer even one red cent for a repair covered by "warranty", this prohibition does NOT apply to repairs under Service Contracts.

 

That's not quite true. The system determines whether or not to apply regenerative breaking or friction braking or a combination of the two.

Are you telling me that if you go sit in your Prius right now that you can't push the brake pedal all the way down while parked no matter how hard you press it? Because I think this is what the OP is describing. I can certainly push the brake down all the way in both Prii. I could not do so in my explorer because the pads would press against the rotor. I can do so in the Prius because there is no direct link to the brakes from the pedal in a Prius EXCEPT for in a failover situation, where the sensor is bypassed and some valves fail-open and the pedal is now directly connected to the brakes.

The click at the bottom of the pedal is real. It may not have been in pre-2012 Prius but I have been in 4 post-2012(gen 3 only) and all have it. Get 4 does not. Here is a thread referencing it a few times from 2 different people. Hill Start Assist Control (HAC) | PriusChat. If you just search brake pedal click hill assist you can see many more references.

So if the system is designed to require you go to the bottom of the pedal for hill start assist, then clearly it is normal for the pedal to go down to the bottom. Now if there is no pressure at all in the pedal stroke simulator device you may have an issue, but you should be able to easily press the pedal all the way down, not to the floor, but to the lowest point of travel of the pedal, which can seem like the floor if you aren't looking carefully.

 

I have just bought my first Prius and had the same thing after having the master cylinder replaced. I am uncertain if the pedal went to the floor before, but I was also told this was normal after the shop re-bled the brakes just to be certain.