This time the brakes didn't work!

[bpwwer]

Here's my strange brake story. This happened on my 2006. After picking it up from the dealer after a normal oil service the brake pedal went to the floor while sitting at a light. I was able to replicate it again while sitting in the driveway. While applying constant pressure to the pedal, it would slowly go to the floor and the vehicle would start rolling forward. Pumping the pedal would bring the brakes back. I was thinking failed master cylinder. Took it back to the dealer and even had the tech ride with me but we couldn't duplicate the problem, strange.

Then a few days later it happened again. Normal braking was fine and after a while, it started behaving normal. Then it happened to my wife once, but again, when she got back it was back to normal. Never happened again for the rest of the time we had the vehicle.

It was as if the master cylinder was temporarily leaking but those don't usually fix themselves.

 

[Land_Shark]

Question: Do you think it is a symptom of the brakes failure to operate correctly or a symptom of the road conditions, i.e. railroad tracks cause tires to momentarily leave the surface and the same thing over bumps. I ask that because by the time you release and re-apply the brakes the terrain conditions could change.

I will say on a dirt washboard road at medium speed the brakes don't work well. Why? Because the tires are not in contact with the ground half of the time. I guess I could install air brakes....

I vote road conditions. When I pull on base, there's a section of smooth-as-glass metal we all drive over. It is about 2 feet long and is right before a stop sign. I'm usually traveling 15-20 mph during braking over this metal section (which is an emergency prop-up hydraulic gate that is laying flat). During that braking period, if there's a little moisture on the metal, I'll slide like I'm on ice - it was weird the first time, but I had no issue immediately identifying what it was. Once on asphalt, braked as normal. ATs aren't as good braking on slippery surfaces.

 

[Bourbonator]

Road conditions don't occur at all 4 wheels at the same time. As your front tires move over whatever strange road condition while braking, wouldn't your rear brakes continue to slow you, and vice-versa? Or am I improperly assuming that whatever computer controlling the brakes can independently account for the conditions at each wheel?

 

[Ron4RNevada]

You guys are ALL nuts and drive way too fast.......:hat:

 

[LandCruiser]

I've had over half a dozen Toyota trucks/SUVs since before I could legally drive, in two different hemispheres.

I have never have any of them unintentionally accelerate or fail to stop or do anything unexpected when the go and stop pedals were pushed.

 

[1engineer]

I've had over half a dozen Toyota trucks/SUVs since before I could legally drive, in two different hemispheres.

I have never have any of them unintentionally accelerate or fail to stop or do anything unexpected when the go and stop pedals were pushed.

Exactly. If they do then I know why, such as a washboard corner down a switchback.

 

[probos]

Ya got a lemon -- sorry. It happens.

 

[NMJack]

Ya got a lemon -- sorry. It happens.

I ain't buying this. Hopefully you're talking about his Toyota, but I don't believe there is such a thing.

 

[probos]

I ain't buying this. Hopefully you're talking about his Toyota, but I don't believe there is such a thing.

You're not buying what,..that he got a lemon? Ok,..so, don't buy it. Hopefully this is another explanation.

Yes, I'm talking about his Toyota -- this is the Toyota 4Runner forum,.....correct?

 

[evtmille]

Still waiting to hear back from Corporate Toyota. Drove it over the weekend with a master tech with diagnostics running but nothing happened. The tech told me there is another 5th generation in the system with similar problems.

Thank you everyone for your input. But nothing explains to me why a modern vehicle would stall after a braking abnormality. Nor could the tech explain it.

He related the first problem to the car going into "limp" mode which clears out after a little while and may or may not been related to the throttle body.

The second event they were able to get codes for the throttle body and replaced it.

The third who knows, maybe an electrical ghost. I'm not waiting for a 4th.

For now just wait and see what Toyota comes back with

 

[Throwback]

Bumping this topic as I had a weird braking situation happen today.

I was driving in the right lane of a divided four lane road running about 45mph. Coming the other way is a gigantic Jeep on a trailer that I stare at as we pass. I look back in front of me just in time to see everyone stopping because a mail truck is stopping at a mail box.

I nail the brakes, hear the front tires let out a good screech, and the nose dives hard. I'm keeping the pedal down waiting for the ABS to kick in, but instead it feels as if braking power is cut and the tires stop screeching, and the hood rises back up to normal level.

I realize that I'm unable to stop in time, I check my left side mirror and slide around the stopped traffic with my foot still hard on the brake and very little braking power being applied to the wheels.

My wife was with me so I didn't go directly to try and duplicate it, but I will tomorrow.

What the heck? It was a very close call and literally felt like once the tires locked up and skidded the computer just cut the braking power by 75% to eliminate the skid, but nearly punted me into the stopped vehicle in front of me.

 

[FORErunner911]

So I've experienced the exact same situation as the OP. It has happened now about 3 times total and today it happened and almost caused an accident.

First two times, I was coming to a slow-stop during some regular traffic. Hit the brakes and it almost felt as if the truck was "kinda" braking, it sort of locked up a bit, but then I quickly let go and re-braked and it was fine. Wasn't a big deal because I was probably only going 10-20 mph.

Today, I needed to brake hard (probably going 40-50), and it did the same thing. I had to swerve to avoid an accident. Obviously worried, I hit the brakes right after the swerve to make sure they worked, and they worked just fine. Turned into a side-street to test them out a few more times before I continued my commute.

To those that are saying this is user-error.... Not quite sure how that's possible. Hit the brakes, they should work.

I've got an appointment scheduled... will try to keep everyone posted.

 

[FORErunner911]

Still waiting to hear back from Corporate Toyota. Drove it over the weekend with a master tech with diagnostics running but nothing happened. The tech told me there is another 5th generation in the system with similar problems.

Thank you everyone for your input. But nothing explains to me why a modern vehicle would stall after a braking abnormality. Nor could the tech explain it.

He related the first problem to the car going into "limp" mode which clears out after a little while and may or may not been related to the throttle body.

The second event they were able to get codes for the throttle body and replaced it.

The third who knows, maybe an electrical ghost. I'm not waiting for a 4th.

For now just wait and see what Toyota comes back with

Any updates? [MENTION=104935]evtmille[/MENTION]

 

[FORErunner911]

he hasnt been here in over 2 years since his last post =/


But I wanna add I've had something similar happen to me a few times driving Mercedes Sprinter ambulances. In wet or icy conditions I've had the ABS dance around and do funny shit requiring getting off the pedal and reapplying. It was usually over railroad crossings or rumble strips, or a few area where the road titties/lane markers were close together. Pedal wants to sink quite a bit while the computer is trying to figure out WTF is going on, then reapplying gives positive braking and feel back. Our fleet guy at Mercedes said this is quasi-normal, but it would stop on its own, we just wouldnt feel the brake effort in the pedal while the ABS is doing its thing. Doesnt mean your ass isnt trying to chew a hole in the seat the first time it happens to you.

Interesting.. I don't think road conditions played a role but it could have - especially when considering it has happened while going very slow (10-20mph) in regular 405 traffic (ie super slow highway driving). It's 70 degrees here in SoCal at 5am when I'm driving to work right now... I don't know... just seems scary.

Upon thinking about it, it does seem as if the power brakes or ABS failed to go for some reason, because although I'm applying 2-3x the the pedal force, the truck IS braking a tiny bit, maybe 10% of it's total available braking power.... weird.

 

[lukeskywalker]

"Autocorrect"? Seriously? C'mon J. You trying to tell me that some guy actually typed "pedal", and a.c. CHANGED it to petal, or peddle?

And, you know what? ..... even IF a.c. was that lame, I'd sure be proofreading what I posted from it.

I'm old school I guess. What, and how, I write speaks to the impression I prefer to convey..... and it's not "you just don't care to go back and fix things". Yup, old school all the way.

The wiseman points to the moon, the imbecile focuses on the finger.

 

[Ray Dunakin]

ABS drives me nuts when I'm off-road. Is there any way to shut it off temporarily?

 

[paddy1337]

ABS drives me nuts when I'm off-road. Is there any way to shut it off temporarily?

I haven't done it on my 4runner (or any recently modern car for that matter), but on previous cars it has been as simple as removing the fuse for ABS.

On a new car I could see this having unintended consequences by affecting 500 other things other than the abs. That's purely assumption.

 

[2nd Chance]

So I recently changed tires to the heavier "E" rated 275 75 70 BFG All Terrain and it has made a significant difference. The other day in the rain my daughters and I did what we call a "Test Brake" in the rain and I was pleasantly surprised as the wheels didn't lock up or screech.

Later today I am going to intentionally panic brake on the rutted road that should replicate all of the past butt puckers and see what happens. I will keep you guys posted.

 

[1jzgte]

Seriously? This thread is about brakes breaking and we've only had one use of "break" for "brake"? Usually the ratio is about 50/50. I'm disappointed here.

If you break your brakes can you brake with your brakes when they break?

 

[tacoyota]

the 4runners ABS system is super intrusive. I can always feel the pedal vibrating and dancing if braking with anything other than normal force. Springs making noises etc....