Broken Rear Toe Link and Traction control and AEB got disabled

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Makaryo

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#1
This happend moments ago. I was on the freeway with autopilot engaged and was about to get on another freeway ramp. I stepped on the brake to take control and the car started veering left and right. Luckily i did not hit any car. It seem to take a while for me to gain some control of the vehicle and has able to park at the side of the free way. When i regained some of my composure i tried to drive again but the car was still veering left and right. Error message is "Traction contol disabled contact tesla service" and "Auto Emergency Braking disabled".i called Tesla road side assistance and the towing company is coming to pick the car up. I'm still shaken up by the experience. Has this happened to anyone?
 

garsh

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#2
Yikes!

Sounds like your brakes failed in a spectacularly bad way. Did it seem to pull in one direction while you were braking, then the other when you let off the brake?
 

SoFlaModel3

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#3
I would certainly freak out if something like that happened fortunately you and the car are aright.

That hasn’t happened to me before.
 

Makaryo

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#4
Yikes!

Sounds like your brakes failed in a spectacularly bad way. Did it seem to pull in one direction while you were braking, then the other when you let off the brake?
Hmmm. I believe the car veered left first and was making a screeching sound. I let go of the brakes, steered right, but then was going way right still made a screeching sound. So the car was zigzagging while it was slowing down. Same thing happened when I tried to drive from a complete stop.
 

Makaryo

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#5
I would certainly freak out if something like that happened fortunately you and the car are aright.

That hasn’t happened to me before.
Yes I'm very fortunate that nothing happend to me and that the cars around me were alert. Middy was driving fine before this happend. Had her for a little over 1 week. The car is with the service center now. I'll try to share the findings here.
 

Brokedoc

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#6
I hope this isn’t a serious bug in 2018.18.13 after tweaking the brake system.

It sounds like the brakes were alternately engaging on opposite sides. Clearly a software issue and very scary and very dangerous.
 

SoFlaModel3

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#7
I hope this isn’t a serious bug in 2018.18.13 after tweaking the brake system.

It sounds like the brakes were alternately engaging on opposite sides. Clearly a software issue and very scary and very dangerous.
I sincerely hope they didn’t rush out the brake fix with limited QA. It all seems fast. That said, I think sometimes Tesla makes it look like things are happening fast but they’ve been in the hopper for a while. :)

Still though your point brings out the negative aspect to the OTA and frequent software updates. Yes we get shiny new toys to play with, but alternatively we have risks of bugs.
 

Makaryo

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#8
I hope this isn’t a serious bug in 2018.18.13 after tweaking the brake system.

It sounds like the brakes were alternately engaging on opposite sides. Clearly a software issue and very scary and very dangerous.
It does appear that the breaks were engaging because when I tried to drive again, the car was slow and was still making the sound.

Yeah I hope it is not a bug with the latest update.
 

SoFlaModel3

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#10
I don't think this is a software issue. This sounds like a mechanical failure of the brakes.
I think I agree — otherwise we’d have widespread reports of issues given how fast this update pushed through.
 
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Brokedoc

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#13
I don't think this is a software issue. This sounds like a mechanical failure of the brakes.
I think I agree — otherwise we’d have widespread reports of issues given how fast this update pushed through.
Def sounds mechanical. Please let us know the resolution!
Wow. I must have completely interpreted something different from the OP for all of you guys to think this is mechanical.

It sounds to me that the brakes are locking on alternate sides to cause the car to swerve from left to right and back. I would have thought a mechanical problem would constantly affect one brake or all brakes. What am I missing?
 

John

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#14
Wow. I must have completely interpreted something different from the OP for all of you guys to think this is mechanical.

It sounds to me that the brakes are locking on alternate sides to cause the car to swerve from left to right and back. I would have thought a mechanical problem would constantly affect one brake or all brakes. What am I missing?
Screeching sound. Mysterious software pulsing on otherwise fine brakes wouldn't screech. Well, that's my thinking, anyway.*

*I'm not a service technician, but I play one on TV.
 

garsh

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#15
Yep, software can't make the brakes "screech".

Plus, the fact that both AEB and Traction Control systems have "given up" indicates that they've detected an issue in their feedback, and no longer believe that the brakes are reacting correctly to their "instructions".

It sounds to me that the brakes are locking on alternate sides to cause the car to swerve from left to right and back.
I doubt that the software can even do that. It's hard to imagine a situation where braking just one side of the other that hard is desirable. Certainly not for AEB. And I can't even think of a situation where traction control would do something that hard.
 
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Brokedoc

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#16
My thinking is that there is a fatal software feedback loop causing the different brake channels to go to max braking then release and goes to another channel. Only with software can ABS control wheel slip and spin at at single wheel.

From the description, it sounds like when the driver was in AP and tried to disengage, individual brake channels started locking instead of all the channels gently braking together. Then, after stopping the car and trying to drive again, the problem continued as the car was still pulling back and forth despite slow speed.

If a brake locks up, it will cause screeching whether it’s mechanical or software. I just can’t think of a mechanical brake part that would cause alternating sides to lock. Perhaps a computer part failure such as a processor or sensor relay could cause this but it still sounds like software.
 

Makaryo

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#17
Do you guys think that all brakes locking up would cause an oversteering effect meaning that when you steer in one direction, the car will still go in that direction even after you steer straight? That is how I remember it felt to me.
 

Makaryo

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#18
But yeah you are right the car seemed to pull back and forth when I drove from a complete stop.

Sorry, It's hard to remember everything that happend because my main thought at that moment was I hope I don't crash!
 

Brokedoc

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#20
Do you guys think that all brakes locking up would cause an oversteering effect meaning that when you steer in one direction, the car will still go in that direction even after you steer straight? That is how I remember it felt to me.
But yeah you are right the car seemed to pull back and forth when I drove from a complete stop.

Sorry, It's hard to remember everything that happend because my main thought at that moment was I hope I don't crash!
When all 4 brakes lock, you should generally continue in the direction of momentum because you mostly lose steering ability. Since the invention of ABS, the steering wheels don’t completely lock so steering ability is preserved if ABS is functioning correctly.

Your description of pulling left and right alternately is very concerning to me for the computer getting confused and locking every other side (or only one wheel) then releasing and going to the other side (or another wheel). If only one side (or one wheel) is locked, the car should pull in that direction constantly. I’ve had a brake caliper freeze on one of my past cars and it would pull to that side but the other 3 brakes were unaffected.