Brakes locked up AGAIN!

I would still check it. You really have nothing too loose and you might not have to buy a booster. It's pretty easy to check and adjust. If it doesnt work your buying a booster

 

My mechanic is going to check it tomorrow, thanks.

 

SO my mechanic told me he it could possible be a bad check valve or problem in the ABS distribution block. Would either of these throw a code? I do not have any brake or check engine lights on.

 

Maybe the valve on the booster but its sold with a booster. I very much doubt its an ABS issue, the brakes stop applying when the vacuum line is disconnected. Something your mechanic already acknowledges.

Just wondering who your mechanic is and what his experience is?

 

Have you checked RockAuto for a Booster?

 

I'll play: did you check all of the brake lines to be sure none are twisted? Did you bleed the brakes to be sure they're are no obstructions? Did you check that the caliper pistons were seating back into the caliper housing? Did you make sure that the correct brake hardware was used for the pads? Did you make sure caliper grease was applied on the caliper bolts?

These things are simple. Though they are very often overlooked and instead people want to go throwing parts at a problem before it is properly diagnosed. If this is what your techs are doing, then you shouldn't be using them. Diagnose the problem properly. There are algorithms to Diagnose these things.

My recommendation is to find a true ASE certified brake mechanic who works at toyota and knows what he is doing. Then pay him to diagnose and fix the problem.

Buy once, cry once. Stop letting unqualified back yard parts swappers throw parts at it until they get lucky.

I don't mean to be brash but I don't like to sugar coat things. You need to know the truth so you can get your ride fixed. It's dangerous to have brakes do this. Your life and the lives of others are counting on your brakes. Leaving that in the hands of unqualified persons is probably not the best idea.

 

The ABS does a complete systems check every time you start the truck. If there were an issue it would code and the ABS Light would also be on.

You need a better mechanic.

 

I took it to a local shop who have been around forever and had work done with them in the past and my friend is a former Nissan tech and has always worked on my vehicles and our friends vehicles. The problem with my brakes started out of no where after owning and driving the truck fine for months without tampering with anything. I went to leave work one night and my peddle was hard as a rock, the brakes were super grabby as I pulled out. We replaced a bad wheel bearing which I already ordered before this and while doing so checked the calipers and pads which were fine.

 

What you really need to understand is that there is a huge difference between a "Parts Swapper" an "Automotive Technician".

 

No lights on in the dash. This all started out of no where one night. I have ABS but no stability control or T/C. I looked up under the dash and the light switch is there and appears fine. I went to work and the truck was fine I left work 8hours later and my pedal was hard as a rock. I started my truck and the peddle released but was super grabby. It slowly locked up about a 1/2 mile down the highway. Replaced a bad wheel bearing and it locked up the follow day on the highway. Took it to a shop who told me it was a bad master cylinder which they replaced along with the flex lines to the calipers and it was fine for a week then one night on the highway headed into work I started getting a steering wheel shake and they locked up again. The peddle goes back to normal function after the truck sits. I drove it the following day and it was fine or at least felt fine normal peddle normal braking. Only seems to lock up on the highway. Had the mechanic at the shop test drive it and he could not get it to lock up on side streets but once on the highway it locked up on him. He said he removed the vacuum line from the booster and the calipers released. I drove it home that day from the shop and it was fine. Nervous to get back on the highway again.

 

I do believe this is a first, but I have to disagree with you here Jimmy. You right that most ABS issues will code and trigger the malfuntion light, but not all. This includes Toyota ABS systems, where I've had personal experience with weak WSS (wheel speed sonsor) signals causing the modualtor pump to activate when the wheel was not skidding. There were no codes logged, and the weak signal was caused by a build up of iron filings on the sensor assumed to be leftover from a previous wheel bearing failure. The sensor read correctly above 5 mph, but below the signal became erratic, causing the unnessary modulation when braking below 5 mph. I've also had GM pickups do the exact same thing when the sensor gap to the tone ring became excessive due to rust scale pushing the sensor away from the knuckle.

Now that said, I'm convinced by the symptoms that the OP's issue is not ABS related, but either a brake pedal pushrod that is too long or a failure of the vacuum valve within the brake booster.

 

I'll agree that what you described would not be found during the ABS Startup self test... Thanks for pointing that out. Most internal ABS issues ( a sticking valve etc ) will show up and code.

 

The first time this happened like I said was out of no where just got into my truck to a rock hard peddle. The following day we replaced the front passenger wheel bearing which was bad and I had it already just didn't put it in right away. The caliper and lines appeared to be fine this truck was never used off road and there is little to no rust on anything, the pads were also like new a lot of life left on them. The truck locked up the follow day same scenario on the highway and then was taken to a shop who replaced my master cylinder and brake fluid after which the truck was fine for a week on the highway and off then one night I got a violent wheel shake as the brakes applied themselves on the highway then released after sitting there about 20min. I took it back to the shop like WTF so he took it for a test drive could not get it to lock up UNTIL he went on the highway it only seems to happen around 50-60mph at which time it locked up and he told me that he removed the vacuum line from the booster which released the brakes. He said he never seen anything like this and was baffled and told me it might be a faulty diaphragm in the booster building pressure when it shouldn't.

 

When I bought the truck last November I drove it with no brake issues. If the pushrod length was to long wouldn't I have noticed something from last Nov until now? This just happened out of no where one day and the fact that my truck was fine going into work and then leaving working the peddle was hard as a rock makes me feel the vacuum escaped? Maybe a faulty check valve?

 

Is there a vacuum valve or anything on the manifold or just the check valve in the booster?

 

What I find strange, backwards even, is that when the vacuum line was removed from the booster, then pedal would get soft again.

I had capped off the vacuum line routing to my brake booster, to do some testing. Within a 1/8 mile the brake pedal had so much pressure, that I had to use an incredible amount of force to get the truck to stop just from 30. Frightening amount. Put the line back on, and good ole brakes again.

Which makes me wonder if there is a vacuum routing that is wrong? Except it should possibly be visually obvious to the OP?

 

I inspected the vacuum line and it appears fine. Is there a way to check he valve in the booster its connected to?

 

For a second time check the push rod and if it's adjusted properly buy a booster. It really is that simple.

 

Try this to test the booster.
http://www.customtacos.com/tech.old...6toyrm/06toypdf/06rmsrc/rm2006ta/04200610.pdf

 

whipper ok I checked the brakes as instructed in the diagram. I started the truck and let it run 2 min the first time the peddle went all the way down but then firmed right back up to being hard as a rock after the 2nd and 3rd no movement. I started the truck again, pressed the peddle down and held it then turned it off and didn't feel any change for 30seconds until I went to pump it and it was hard as a rock again. I pulled the check valve out and that seems ok i only get ventilation from the end it says I am.