Since the last thread was hijacked by some people with nothing better to do than argue about who's car's headlights are better.
First it was the throttle body yesterday the brakes didn't work. 2015 4Runner with 8000 miles, wife pushed the brake peddle to the floor and nothing happened, let off and the second time fortunately the brakes locked before she rear ended the car in front of her, so close the guy got out to check to see if she was ok. Oh and then the car just died.
Anyone else have similar problems? Just a bad car or is Toyota's legandary reliability coming to an end. My wife is a life long Toyota driver and used to race in the Toyota Fun race in Venezuela in several different Machito's (wish we could get one here) and this is our second 4Runner together! I didn't think we bought a Jeep.
What happened with the throttle body before?
Honestly the description of events that you've written sound odd to me. The problem is that "pushed to the floor" while concise and accurate is also very vague and uninformative in this particular case. What further complicates things is that most people are not over analyzing how they are applying the brakes and due to the very consistent feedback with these hydraulically assisted systems, it is easy to misjudge your actual brake engagement on feel alone.
That being said, IF the pedal went to the floor the first time and then the second time it engaged; it could indicate an issue with the master cylinder portion of the hydraulically assisted braking system (I had a similar issue in my 4th gen:
http://www.toyota-4runner.org/4th-gen-t4rs/107245-inconsistent-brake-pedal-travel.html) Though a sudden onset seems a bit odd, but not out of the line of plausibility. The issue that bothers me is that the supposed issue went away after the initial incident, if the master cylinder portion did fail you'd be able to consistently replicate the issue to varying degrees.
Additionally, the "Assisted Braking" feature is VERY touchy. If the Skid Control ECU saw the operator do a double-tap on the brakes with a sharp increase in brake pressure in a short timeframe it will kick into overdrive and engage full power to the system. When that happens, these vehicles STOP; it's pretty damn impressive! Additionally, the sharp contrast between "normal/light braking" and the "brake assist" mode is so severe I wouldn't fault an operator for feeling that the system was malfunctioning.
Something else to note (and this is more my personal theory) is that the 4th gen & 5th gen Hydraulically Assisted Braking Systems are notorious for a "spongy/soft" feeling pedal because they have extremely consistent brake pedal feel when applying the brakes. This seems to stem from the fact that unlike our hybrid vehicles which use a valve to block off the pedal passage and provide a false feedback to the customer; the 4th & 5th gen units lack this "feedback generator" circuit in the hydraulic system and hydraulic assistance is directly applied to the hydraulic circuit so pedal effort is very light and consistent.
I almost wish Toyota had installed some sort of variable "feedback" circuit (they couldn't effectively block off operator input completely like the hybrid systems because then the vehicle wouldn't stop; this only works with hybrid vehicles because the first 1/4~1/3 travel of brake pedal depression is completely ignored hydraulically by the vehicle in favor of regenerative braking.)
arent the brakes designed to overpower the engine?
Almost every modern vehicle (even GMs and Ford trucks with their typically soft/sluggish brakes) can overpower the engine easily. I've tested this on a few Toyota vehicles including my 4.7L equipped 4th Gen at Full Throttle at freeway speeds. Unfortunately many people are quick to ignore the human error part of the equation, particularly so when figures of authority and emotions are thrown around. While the above link does state that the operator was a LEO, that does not mean that human error was not a factor. The assumption people make is that because he/she is an LEO that somehow they are masters of vehicle driving technique (which isn't completely erroneous since they do get additional training in driving techniques,) but that doesn't mean the operator couldn't have been caught by surprise and/or not as competent as most assume. Without going into this in great detail (there's been plenty of threads that I and others have gone in great detail on regarding the above situation and others relating to UAI in Toyotas, so I do recommend if you are interested, to search and read through those) the simple fact is that the brakes in every Toyota vehicle will overpower the engine/hybrid system without issue and trying to use links such as the above really comes down to shock & awe tactics without proper context and understanding.
The data clearly shows the people involved in these incidents were elderly or FOB. The media-induced hysteria forced Toyota to pay up.
