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

[Manhattan]

Did you rule out the ABS - control module, wheel speed sensor, etc?
If the truck "thinks" one wheel is going faster than the other, it will apply the brakes.

 

[MongooseGA]

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.

So $2800 later... sigh. She drives great!

I had exactly this in my old '00. Mine was taken care of by bringing the nose back down a little bit to 21.5". It had been up over 22.5".

I imagine it was really a symptom of a bad rack though, just highlighted by the lift.

 

[MH_Stevens]

UPDATE: Happened again AND also once brakes applied on BOTH sides when going down hill. It WAS the VSC light that flashed. Everything goes back to normal after applying brake pedal.
Recently did some hard off-road and rock crawling with drop-offs so could sensors just be dirty? I will remove wheels and wash and clean wheels and brakes.

 

[MongooseGA]

It's possible but I don't think that's your culprit. I wheel the heck out of mine, gotten the entire underside submerged in mud many times, and it's not been any sort of issue on my '05.

 

[I Lean]

I fully realize it's not a "fix", but I have zero regrets about disabling my VSC completely. It hasn't tried to kill me at all since then.

Procedure for doing it is here: VSC OFF switch install.

 

[mobi-arc]

My brother accidentally put power steering fluid in the brake fluid reservoir which subsequently caused the brakes to actuate by themselves. The fix was to flush the brake system completely, then refill with fresh correct fluid.

 

[MH_Stevens]

Just realized I lost the cap to the brake fluid resavoir and could not find a replacement so have a non standard cover. Might this have caused an issue?

 

[MH_Stevens]

UPDATE. Brakes still occasionally come on but NOT just one side as I said before. Also no warning lights have I seen recently but I get the warning bell sound. More detail on how to check the steering rack would be great as I so far do not see an issue.

 

[2001LC]

@MH_Stevens

If you were in my neck of the woods (Denver) I just have you come by, and I'd inspect for you.

Zero point calibration is not something normal needed. VGRS equip systems (lexus). These system when battery disconnected will flash VGRS on dash. One just needs to drive in a straight line a few 100 yards at 35km. ~25MPH. VGRS Light goes off. Than make normal right and left turns. I like doing figure 8s.

I get sense your wheel bearings are loose, you may have bad ball joints and or TRE, power steering issues along with brake issues. Your brake fluid may also be low.

If this the case were looking at and under maintained rig and or improperly maintained. I find dealership maintained, improperly maintained all the time. INDY shop can really mess these up.

I've a number of threads you can read through in my links in signature line. Start with master (first link) and look at my restore projects. These go go through very extensiveness inspection and restore work. Look at Snowy and The Unicorn for most in depth. These are not step by step, but over views. Reading these may get you on to right tract. If you don't have the mechanical tools and skills. I suggest you find a shop that specialize in 100 series. Or club member in your area, that can help you inspect.

Get a copy of your years maintenance schedule. It has something required done every 5 or 7K miles. Mostly fluids. But other things like inspecting area, wheel bearing service, etc... Don't just settle for what you can find in parts, go after OEM parts. Be them from Toyota or Toyota's suppliers like Denso, NGK and Asian to name a few.

Build a list, start with safety stuff first.

Good luck my friend.

Edited to correct error in ZPC being only LX. It is done on LX or LC.

 

[jLB]

Zero point calibration is not something normal needed and applies to VGRS equip systems (lexus). These system when battery disconnected will flash VGRS on dash. One just needs to drive in a straight line a few 100 yards at 35km. ~25MPH. VGRS Light goes off. Than make normal right and left turns. I like doing figure 8s.

I'd agree that a "Zero Point Calibration" is not something that is normally needed, and the majority of your post is filled with excellent advice, as usual.

I believe that you are mistaken on a "Zero Point Calibration" applying only to VGRS equipped Lexus vehicles. It is my understanding that the "Zero Point Calibration" applies to all VSC equipped vehicles and it is the method used to recalibrate the inputs into the VSC system (steering angle sensor, deceleration sensor, and yaw rate sensor). There is a mention of the ZPC procedure in the FSM for a 2000 TLC under the diagnostics section for the VSC system.

If you disconnect the battery on a VGRS equipped vehicle, you will get a VGRS light, but I don't believe it has anything to do with a ZPC for VSC.

 

[2001LC]

Thanks, I stand corrected! I was think only Lexus, my bad.
I so often see in mud someone stating "don't disconnect the battery or you'll have to take in for ZPC". That for sure is incorrect, LX or LC.

 

[MH_Stevens]

UPDATE:
It IS the steering rack bushings. I'll search for a vid to replace but any advice appreciated.

 

[menancyandsam]

UPDATE:
It IS the steering rack bushings. I'll search for a vid to replace but any advice appreciated.

How much play do you have in the steering rack bushings, wondering if I should just replace mine.

 

[MH_Stevens]

My bushing are almost gone. The rack moves like there were no bushings there!. Funny thing is steering is not bad just the abs messing with brakes. I could not remove my bushings, the are in very tight and not at all accessible so my truck is going into the shop in the morning.

 

[MH_Stevens]

OK so I need steering rack bushings but I can't find them. Part number and link anyone?

 

[trdcorolla]

Per a quick mud search the D bushing is 45517-60010

 

[2001LC]

OK so I need steering rack bushings but I can't find them. Part number and link anyone?

Making call that it is steering rack bushing is a difficult one. That rack with OEM bushing is designed to move side to side. One thing I see with the newer racks (03-07) when bushing have gone or going bad. Is what loos like a washer (actually a cup top) on top of mount under bolt PS. will turn about 5 degrees. That is clue one. If rack lifts as steering wheel turns is clue two. If steering wonders on HWY that is clue three.
Wondering can also be caused by things like alignment, loose wheel bearing, bad ball joints, bad inner or TRE, control arm bushings all must be to spec..

Bushing cup has rubber that holds it in place. As rubber goes bad the cup turns (washer under bolt)

Rack bushings:

Steering rack / bushing opinions

Sorry for another thread on steering racks. I am about to replace my steering rack bushings with SuperPro poly bushings, but I wanted to get a few opinions first. I am pretty sure my original bushings are shot, but it seems the rack itself as well as the TREs are in good shape. There is no fluid...

forum.ih8mud.com

Toyota only sells to "D" bushing for PS side, that is used 98-02 racks. They do not sell the mounting bushing for any 100 series racks.

For mounting bushing you've two basically two choices. Ploy or rubber (OE style).

Slee Off road carries the poly. IIRC they are White lighting poly bushing.
2003-2007 Poly SOF1302 Slee PN #

1998-2002 steering rack bushings

I have installed rubber bushings. But only with steering rack out. I don't know if it can be done with rack in place.

 

[2001LC]

I had one 00 LX470 that mounting bushing were so shot. The steering wheel stayed turned long after wheels came back to straight. It wondered all over the road, scary really. It did not set off VSC or ABS.
I've seen many cases of loose wheels bearing causing ABS to get signal a wheel speed is slow then brake other wheel, like what seems described in OP. The wheel speed sensor reads the wheel hub speed. If bearing are loose it can be confused on speed hub is turning.

Wheel speed sensor reads these teeth on back of wheel hub.

Very easy to test for loose wheel bearings. Did you?

 

[stupidgringo]

Just to add another data point to the conversation. I had the vsc alarm/blinking light with self-applied brakes problem. It was solved with new steering rack bushings - the old ones were shot. Another symptom I had was cruise control would no longer hold. I observed that shortly before I had my first vsc braking issue. Cruise control issue was also solved by the new steering rack bushings. If you're having the vsc braking issue, check your cruise control. If it's not working, that may point to steering rack bushings as the solution.

 

[MH_Stevens]

My bushings ARE shot and I have got new ones, BUT how do I decide if rack needs replacing. With 222k on it is it likely still good?