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Brake Pedal Issues

Discussion in '5th Gen 4Runners (2010+)' started by katheriner4runner, Nov 16, 2020.

  1. Nov 16, 2020 at 3:19 PM
    #1
    katheriner4runner

    katheriner4runner [OP] New Member

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    I just bought a 2020 4runner TRD in July. No modifications and barely hitting 5K miles.

    Over the last week, the brake pedal has failed 3 times. All times have been around 30-40 MPH, no cars in front of me. As I slowly press the brake down it randomly seemed to depress lose pressure and end up all the on the floor while not stopping. As I release the brake and the press again, it seems to work again.

    I figured it could be a master cylinder or abs issue, but the dealer is saying they looked it over and nothing is wrong. They scanned the car and it showed the emergency brake system setting off at those three exact times. The service advisor said if the emergency braking system was activated it could be why the brake pedal went to the floor. That makes no sense to me. Under no circumstances should the pedal go completely to the floor. In addition, typically when the emergency braking goes off, lights and alarms go off in the car. None of that happened. There was also no reason for the car to emergency brake.

    Any suggestions? The dealer wants me to pick it up but frankly I'm not comfortable driving it.

    (edited for some clarification)
     
    Last edited: Nov 17, 2020
  2. Nov 16, 2020 at 3:41 PM
    #2
    jmkulbeth

    jmkulbeth New Member

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    I'd be inclined to try another dealer. Brakes are kinda important! As for losing pressure by applying the emergency brake, I have trouble believing that. I'm new to Toyota's and 4Runners, but emergency brakes are generally mechanically linked to the brakes so they still work even if you lose fluid.

    Any chance you used the emergency brake to stop when the service brake didn't respond? That'd explain what they saw on the computer. If you didn't use the emergency brake, what did you do to stop... Maybe pump the pedal?

    Did they check the fluid level?
    Did they check the lines for air?
    Did they inspect the pedal to make sure nothing was physically messed up there?
    Would they be willing to stand in front of it while you accelerate towards them and brake at the last minute?
     
  3. Nov 16, 2020 at 4:43 PM
    #3
    Agent_Outside

    Agent_Outside New Member

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    what was your last vehicle and are you familiar with ABS activation and what it feels like?

    (Not being sarcastic, serious question)
     
  4. Nov 17, 2020 at 9:32 AM
    #4
    katheriner4runner

    katheriner4runner [OP] New Member

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    I am familiar with ABS. From my experience ABS can cause the pedal to drop a little and pulsate. None of that happened. Pedal just loosely went to the floor and no stopping. No reason for ABS to go off in the 3 situations either.
     
  5. Nov 17, 2020 at 9:41 AM
    #5
    katheriner4runner

    katheriner4runner [OP] New Member

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    Sorry, to clarify it was the emergency braking system getting set off (pre-sense I think they call it?), not the actually emergency brake. What is odd is that when that system goes off there is normally lights and warning sounds which there were not any of. I told them I am not picking it up and to keep looking, so I am waiting to see what else they have physically looked at other than just scanning the car for codes. I checked the fluid level after it initially happened and fluid was full and didn't see any leaks under the car.
     
  6. Nov 17, 2020 at 10:37 AM
    #6
    dcaplan

    dcaplan New Member

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    I wonder if the loss of pressure at the foot is the pre-sense applying the brakes therefore there would be a change in pressure at the brake pedal because technically the brakes are already activated? When this happened did the truck slow down at all on its own or was there any indication the pre-sense system was being activated? I agree, if a code of the braking system coincides with these incidents than something is wrong. If I know anything about Toyota is that they take braking and acceleration pretty seriously now. Ask them if they would write you a letter stating that there is no fault in the braking system that you could show your insurance company if you rear-ended someone or worse, ran someone down crossing the road. I like this "Would they be willing to stand in front of it while you accelerate towards them and brake at the last minute?" the ultimate test of "how sure are you?
     
  7. Nov 17, 2020 at 10:42 AM
    #7
    katheriner4runner

    katheriner4runner [OP] New Member

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    That was the first thought, but the pedal went completely to the floor as if no brake fluid in the car and the car did not slow down whatsoever. There was no indication of the pre-sense system being active either. No light, alarms are anything. A letter is a good idea.
     
  8. Nov 17, 2020 at 10:49 AM
    #8
    dcaplan

    dcaplan New Member

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    You might want to also ask them why the pre-sense was activated but you have never seen any indication it was, no lights, alarms, sounds, etc yet it is throwing codes that it did activate.
     
  9. Nov 20, 2020 at 11:42 AM
    #9
    katheriner4runner

    katheriner4runner [OP] New Member

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    Since this seems to be an issue for other people in the forums, I thought I would update everyone in hopes it helps someone. I ended up escalating my issue with Toyota Corporate because the dealer could not find anything wrong and wanted to send the car home. They apparently sent a field tech and were able to duplicate the issue but can not pin point the cause. They will be replacing the entire brake system on the car and I was told will be sending the part to Japan to investigate since it is a major safety issue.
     
  10. Nov 20, 2020 at 11:55 AM
    #10
    dcaplan

    dcaplan New Member

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    Well that is good news! I wonder what replacing the braking system means. Does it mean the master cylinder or something else? I guess in my mind as I was reading that is that the would rip out all of the brake lines, callipers, cylinder and any other parts related to the braking system which obviously isn't really logical. If they can't pin-point what is failing how do they know what to replace?
     
  11. Nov 20, 2020 at 12:15 PM
    #11
    katheriner4runner

    katheriner4runner [OP] New Member

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    My guess is that they are just replacing every part that could possibly cause this issue. They mentioned replacing the master cylinder, abs control module and abs brake actuator among other things. My best guess is it has something to do with the ABS. My concern is that who's to say the new parts don't have the same issue if they don't know the cause and it seems there are other vehicles with the same problem.
     
  12. Nov 20, 2020 at 6:45 PM
    #12
    Snickel Fritz

    Snickel Fritz This member likes turtles.

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    Welcome to the forum, though I am sorry for the early experiences you've been having as a 4R owner... glad to see that you're likely going to be okay, however!
    Do keep us updated!
     
  13. Nov 20, 2020 at 7:04 PM
    #13
    glwood54

    glwood54 Stop making me buy stuff!

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    I don't see this specifically mentioned, but what is the likelihood that this problem is possibly related to an issue with the TSS?

    If a malfunction in the TSS is the cause of a disappearing brake pedal and loss of braking, Toyota has a huge problem on its hands. Remember the "unintednded acceleration" fiasco?

    Hopefully this is a one-off occurrence. PITA for the OP, though. Good luck with the fix.
     
    Last edited: Nov 21, 2020
    Snickel Fritz likes this.
  14. Dec 1, 2020 at 11:30 AM
    #14
    koukimonster

    koukimonster DYNO4

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    Scary. My bet is that it has something to do with these stupid pre-collision systems. Thanks, Toyota.. put a bunch of crap on my truck so that idiots will pay LESS attention while driving, just so that they can fail and send my paying-attention-ass into the ditch or car in front. I'm rolling my eyes as hard as I can right now...

    I fear for the future of driving. Seems like every time I drive my new truck, one of these damn systems is triggering a new light on my dash that I have to go look up out of fear of something being broken. Nope, it's always just a little dirt, ice, or maybe the damn thing is just moody that day...
     

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