Brakes Applied Themselves at Speed and Cruiser Pulled Sharp to Left (1 Viewer)

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I've read up on self-applying brakes in general but find nothing specific to the above symptom. Seems to me for some reason one of the two left side brakes must have applied of the own volition but I can not deduce any mechanism for this to happen. Rotors and pads seem OK. This happened close to home so I returned and have not again test driven yet. Only happened once. Brake fluid reservoir cap is missing and sealed with bung but it has been this way for 20,000 miles. Brake fluid was changed about 1,000 miles back.
 
VSC?

Did any "alarms" sound when it happened?
 
No. No messages or lights.
 
When my 2000 did that (a lot) it ended up being the steering rack triggering the VSC. Sometimes it beeped, sometimes it didn't but it was such a sh*tstorm when it did it I'm not sure that I just didn't notice the flashing lights and beeping.
 
I too thought lights might have flashed and been missed in the panic as it was a severely dangerous situation being thrown across the road into oncoming traffic. At that time I instinctively braked hard and when cruiser had slowed the situation was corrected.
What was your issue with the steering rack that cause your issue and was your issue also only on the left side?
 
Could be ABS related - wheel/speed sensor.
 
I too thought lights might have flashed and been missed in the panic as it was a severely dangerous situation being thrown across the road into oncoming traffic. At that time I instinctively braked hard and when cruiser had slowed the situation was corrected.
What was your issue with the steering rack that cause your issue and was your issue also only on the left side?

The primary symptom was hard left side braking which sometimes pulled me into the wrong lane. Every now and then it would seem to switch between wheels.

The steering rack was work out. It started out as a rare occurrence, most of the time just the annoyance of the cruise kicking off in a turn, and I thought I had a wheel speed sensor going out. Pricing those ruled that out (not really but they are expensive and you can't buy just one!). I was in the Ouray, CO area early one winter and had been in some 6"-8" snow, nothing horrible but I thought it was the snow and a wheel sensor issue causing the problem. It locked up hard going around the curves south of Ironton. A little later I rounded the hard right hand curve as you leave Silverton to the south and it locked up again. At Durango I found a car wash and sprayed the underside real good and the rest of the trip back to Texas all I had to contend with was the cruise control turning off in left hand curves ( think... it's been a while ago so it may have been right hand curves). It seemed like a wheel speed sensor may have been dirty but it still locked up from time to time and it's real annoying to have to reset the cruise all of the time. Since I knew the rack was sloppy I bit the bullet, ordered one, and changed it. Not a fun job but doable. Once that was done there were no more lockup or cruise issues and the LC drove a lot better. No more wandering from side to side. And I still have the stock wheel speed sensors.

What kind of mileage do you have.
 
I hope when you were in Durango you stopped at the Station Hotel and had some of their Octoberfest brew. I once lived in Houston and did the Houston to Silverton run a few times. Used to go up to Crystal lake. My milage is 220K and last week I did some very hard rock crawling and gravel roads, so maybe my rack is wearing out. However I don't see how the worn rack caused one side to brake?
 
I hope when you were in Durango you stopped at the Station Hotel and had some of their Octoberfest brew. I once lived in Houston and did the Houston to Silverton run a few times. Used to go up to Crystal lake. My mileage is 220K and last week I did some very hard rock crawling and gravel roads, so maybe my rack is wearing out. However I don't see how the worn rack caused one side to brake?

I live (temporarily) about 45 min south of Durango (Bloomfield). I think I've been there but not recently. Now I have a place to go. Never live where you like to vacation.

I had to replace mine around 180k

I don't understand steering geometry well enough to explain it but I think the wheel speed changes with the steering angle. I know the outside wheel travels further and therefor slower than the inside wheel but if the rack is sloppy the wheel angle is "flopping"... like lined up, toed out, then toed in, and that affects wheel speed. The computer sees that as if a wheel is slipping? So, it applies the brake to the wheel that's slipping. I also packed my wheel bearings and replaced the axles when I replaced the rack. <-- this could be total BS but it might prompt someone to jump in and explain it correctly.
 
But when my issue happened I was driving straight but it was a windy road. Are you saying it needs the differential to be in play for this scenario to happen? Like you I hope others join in.
 
More like the rack has enough slop that when pointed straight the wheels are actually wandering left to right even when you're driving straight, but not necessarily together (one turns slightly left while the other turns slightly right). I'm fairly certain that the sudden braking is the VSC trying to stop the wheel that it thinks is spinning (by applying brake).
 
This happened to me on my 2000- mine would happen every time I went around a certain corner at about 40 mph, VSC would start flashing and beep until I slowed down under 25 mph or so. Sometimes the brakes would apply and jerk the vehicle. Thought it was a wheel sensor or something ABS related (hopefully). Turned out to be the steering rack. :doh:

So $2800 later... sigh. She drives great!
 
Been researching steering rack issues here but don't see how to diagnose steering rack issues to decide what repairs may be necessary.
 
Been researching steering rack issues here but don't see how to diagnose steering rack issues to decide what repairs may be necessary.
As said, there will be some wandering as you're driving straight, you will be putting in more corrections than normal. Do you feel like the vehicle drives perfectly straight on it's own?
 
Never noticed a steering problem and yes on a good road vehicle will go straight no hands on wheel.
 
On my son's vehicle we had an issue with VSC after replacing the steering rack. I'm driving him back toward college in his vehicle, we take a fast clover leaf exit, and all hell starts breaking loose. He says "Oh yeah, it does that sometimes". (I think he has some of his mom's genes sometimes). A "zero point calibration" in Techstream, resetting the yaw sensor and steering angle sensor fixed our issue.
 
A "zero point calibration" in Techstream, resetting the yaw sensor and steering angle sensor fixed our issue.

Is that a dealer only procedure?
 
Is that a dealer only procedure?

Well, that may have been Toyota's original intent, but no, I did it myself w/ a mini-VCI cable, Techstream and Dell tablet.

A good Techstream starting point might be this thread:


There's probably a thread here explaining the procedure, but this is what I found first:



Alternative method (I've personally never done it this way):

 
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An easy test is to start the truck and while still in park get down on the ground where you can see the steering rack. Have someone turn the steering wheel all the way to the left then to the right. If you see the rack move in relation to the frame crossmember it is bolted to then your bushings need to be replaced.

My lx steering had felt perfect when this occurred at 60 mph while pulling a trailer, after replacing the bushings the steering was much more responsive.
 
Don't find any problems with steering. Going straight truck responds to the slightest turn of the wheel. No free play?
 

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