Poll on total brake failure in 100 series (6 Viewers)

[Amplificus]

So this is the sequence of events as to the best of my memory. Everything was working fine, brakes felt normal on the way to the ice store to pick up dry ice for the weekend camping trip. I was loaded up with all gear and my two boys in the back seat and since this was the first trip with the new car, I was curious if I would get any reaction from the AHC (I have not checked pressures yet since I bought the car in December).

Side Note: I do remember that the brake fluid level was above max after I took it to service @ Lexus dealership, so you might be on to something about the brake fluid corroding the wire connection.

As I pulled into the parking lot, it seemed like I heard a crunching sound coming from the drivetrain, but thinking back it mayI have been the crumbling cement under the tires. I pull in, reverse to position the car to pull into a parking spot and warning lights appear and go crazy complete with the high pitch warning tone. I immediately think its the transmission, transfer case or the differentials since I heard a crunching noise before. There are no fluids leaking, and at this time I learn that there is no transmission dipstick to check fluids (hahaha). So I then try to shift transfer case into N and L, still trying to diagnose what I thought was a drivetrain issue. I put the gear back to H but the transmission was having some trouble going back into P. I got it there with more force and a little grinding (oops!). After walking around the car again scratching my head in confusion, I got back in and started reversing a little, then driving forward, reversing thenout of nowhere with no indication, the brake pedal goes to the floor. By pressing hard at the end of the pedal stroke I could feel a very small amount of brakes, but not even enough to stop the car from rolling fwd when in D. I used the hand brake to stop and started searching the internet and I came to realize that "I was experiencing what I have seen every day at the top of 100-series forum on ih8mud!"

Anyway, I will definitely ask to keep all the parts the dealer removes and post pics when I see them, or report back any news.

 

[2001LC]

So this is the sequence of events as to the best of my memory. Everything was working fine, brakes felt normal on the way to the ice store to pick up dry ice for the weekend camping trip. I was loaded up with all gear and my two boys in the back seat and since this was the first trip with the new car, I was curious if I would get any reaction from the AHC (I have not checked pressures yet since I bought the car in December).

Side Note: I do remember that the brake fluid level was above max after I took it to service @ Lexus dealership, so you might be on to something about the brake fluid corroding the wire connection.

As I pulled into the parking lot, it seemed like I heard a crunching sound coming from the drivetrain, but thinking back it mayI have been the crumbling cement under the tires. I pull in, reverse to position the car to pull into a parking spot and warning lights appear and go crazy complete with the high pitch warning tone. I immediately think its the transmission, transfer case or the differentials since I heard a crunching noise before. There are no fluids leaking, and at this time I learn that there is no transmission dipstick to check fluids (hahaha). So I then try to shift transfer case into N and L, still trying to diagnose what I thought was a drivetrain issue. I put the gear back to H but the transmission was having some trouble going back into P. I got it there with more force and a little grinding (oops!). After walking around the car again scratching my head in confusion, I got back in and started reversing a little, then driving forward, reversing thenout of nowhere with no indication, the brake pedal goes to the floor. By pressing hard at the end of the pedal stroke I could feel a very small amount of brakes, but not even enough to stop the car from rolling fwd when in D. I used the hand brake to stop and started searching the internet and I came to realize that "I was experiencing what I have seen every day at the top of 100-series forum on ih8mud!"

Anyway, I will definitely ask to keep all the parts the dealer removes and post pics when I see them, or report back any news.

Thanks, good recall!. You did the right thing investigating after alarm sounded, from a parking spot.

I'm very interested in your old parts and would like to have them.
I've been tearing down to investigate, any I can get my hands on.

Highlights:
History;

1. No mention of inspecting a recently purchased 13 yr old w175K (06LX)
2. Lexus Dealership recent serviced (unknown for what, likely O,F&L).
3. Brakes reservoir observed overfilled.
4. No known brake fluid leaks.
5. Strange sound heard before brake alarm. May be just tires on loose cement/gravel.

Warning;

1. Brake warning. Dash lights & alarm sounded. Presumably while foot on brake pedal bleeding off brake system assist pressure, as was reversing into parking spot.

Brakes use continued after warning alarm. Presumably, foot on and off brake pedal minimum of 3 times after alarm and pedal held down.

1. Continued using brakes. While trying to diagnose sound, shifting through transmission gears and transfer case. Presumably foot on brake pedal.
2. Started and stop engine (IG key off and on), presumably. More times foot on brake pedal.

Brake loss.

1. Minimal brake at bottom of pedal, after pressing pedal multiple times after alarm sounded.

Note: Reservoir overfilled, for few hours or days would not give time to corrode wires. But overfilling was likely done over the years. It's a very common problem. Once brake fluid gets into boot the corrosion would start, which takes time. There may be other reason for corrosion on wires. But I've not found a logical explanation other than brake fluid.

It also possible it was not the motor failure. But something else, or motor didn't get switched on. But most common based on your outline is motor failed to run. The why will take tearing down and inspecting.

Assuming reservoir still has fluid (no leak). Dealership will likely do one of two things. Replace booster assembly $1.5k to $2.5K or replace entire brake master assembly with booster $4k to $5K. In some cases you get a mechanic that digs to find that one component $500 to $2K, but not often. They will use new OEM parts only at Toyota or Lexus Dealership.

 

[2001LC]

Often we've read here sudden and without warning. That is unlikely. It just drivers ignoring the warns. After parking for hours (over night) the pressure does bleed down some. So start-up is time we'd get least advance warning. But if pressure does not come up very quickly, alarm sound in that event also. If alarm broken or disabled then we still have dash lights.

When we turn IG key to ON. Listen and you'll hear a motor run. Many think this is fuel pump, it is not! It is your brake booster motor running bring up pressure filling accumulator.

I tell my GF: If alarm sounds or brake lights comes on or both. Pull to side of road and stop. Do not drive, just call me. It should not happen but; Be prepared to press pedal to the floor and use hand brake, along with downshift (engine braking) to reduce speed, then shift to N as speed drops too come to stop.

 

[Amplificus]

I got a response from the dealership, they are going to replace the brake master assembly for $4275. ouch....

I did request to save all of the old parts and will report back when I have news.

 

[2001LC]

Saw that coming, ouch. They just can'y take the liability to not replace.

 

[MountaineerLC]

I got a response from the dealership, they are going to replace the brake master assembly for $4275. ouch....

I did request to save all of the old parts and will report back when I have news.

Ouch! That's over half of what I paid for my truck!!!

 

[Hugh Heifer]

At that price I would have looked for used parts. But I also understand why you didn't.

 

[Amplificus]

So after some overnight parts from Japan, got it back from the stealership yesterday. Here are some pics of the connector under the brake master cylinder unit.

Contacts at the motor side looked brand new.

 

[2001LC]

PM me if willing to ship that to me for research. This is exactly what I'm looking for to tear apart!

I also got a PM from east cost of bad motor with wire corrosion.

I'm becoming more and more a convinced, wire corrosion is a warning sign. I'm sticking with my recommendation that those found with corroded wires need to service the master, by replacing wire and inspecting inside of motor.

 

[Amplificus]

I pm'ed you.

I really think that the boot over the screw terminals traps in water after engine washing/fording a river, or lots of rain. Just because it is facing up, acts like a bowl and holds water in.

I would suggest to other 100-series owners that they at least puncture a small hole into the bottom of the boot to help drain this area, if not fill with silicone. I would say that I would risk partial water exposure and have it dry quickly, than having it sit in a pool and corrode much quicker.

 

[2001LC]

I responded to PM, Thank You!

Okay, here goes yet one more of my long post, as I get on my soap box!

I've posted in a few threads, where you'll see I punch a hole and also fill boot(s) with dielectric grease.

But I feel number one prevention is do not Overfilling reservoir. Don't Do IT! Brake fluid is hygroscopic.

Here is my thinking and why:

I first thought just as you, water getting in the boot. Although driving through rain, snow, deep water it doesn't really get up to area. So I assumed it was from washing engine bay. But no wire corrosion on my 01LC (The King) which I washed engine bay at least once a year for 14 + years, you could eat off engine. Also drove in the rain and snow. No corrosion on wires.

I now inspect for this corrosion condition on brake master wires always. I've see engine bays of low miles rigs (50 to 130K 05-07), that look like engine bay never washed. No real way to known if ever washed, but clues said not washed. Yet found corrosion. How did moisture get in wire boot(s). Yet in early stage of corrosion I find thick wet gunk. Remove boot leaving off and it hardens and corrosives action goes to work.
First inspection of a 2007 from GA/TX. You're looking at reflection in inspection mirror of boot pealed back and wires exposed.

I thought perhaps leak from ABS unit was getting through leads internally, then into boot. But I took/smashed apart the ABS unit. I really don't think fluid can get through ABS into boot. Plastic is cast around leads and snake up through the ABS plastic. Leads are deeply in-bedded in plastic.

When I considered it coming through the ABS. I realized brake fluid is hygroscopic. Brake fluid attracts and holds moisture. But how could it be getting into boots. I'm 99.9% sure it's not leaking from ABS. So how then is brake fluid getting to the area? Leaks, spillage, what???

Over-filling of reservoir is second common thread (1st corroded wire) I'm finding to these failures. I find about 30% of all rigs over-filled. This includes Toyota or Lexus Dealership maintain with spotless service records. Shop tech's see reservoir low and tops with best of intentions. They think fluid low due to pad wear, which is normal thinking. But they fail to read what Toyota felt so important they embossed on the reservoir. A procedure to evacuate brake fluid from accumulator into reservoir before topping.

During normal driving over-filled reservoir, excess fluid is pushed out cap and grommets. This gets on boots and IMHO into boots.

Now the second question I have is:
Does the change of resistance in the wire, damage ABS and reduce life of motor. This is why I'm asking those that have had failures.
"Is wire corroded"?
What failed on brakes master?
It's also why I'm asking for the old brake master parts. I take apart and inspect for what, why and common threads.

I've one of the highest mileage 100 series (00LX) in the country at over 350K miles, that I'm driving. It lived in CN first few years (late 99). Spent some time in Boston. Has more rust then I'll usually buy, work on or see here in the west. Not really bad rust, but works me harder and has gotten under sheathing of some wiring (blueing oxidation). I've door lock motor issues and hinges of DS door are worn out. Steering column needs work as it's loose. It was Lexus Dealer maintained. The records are the thickest I've every seen, and I've yet to get the first two years of records as it lived in CN. This rigs a good test bed. Yet it's wires have no corrosion. Motor is still working and seems fine. I will be pulling the accumulator pump motor and inspecting brushes, bearings and commutator one day. But that means replacing the very expensive the wires, FSM states non re-usable. So it makes for a very price inspection. For now I just made sure brakes are in tip top condition and pass all test. I also PM the e-brake with new shoe.

If I get a brake light and or alarm. I'll pull off road at once. I know I'll have limited number of time I CAN pressing pedal before assistance pressure is LOST!

 

[Amplificus]

I guess that if brake fluid gets in there, a small hole would let that drain as well?

I'm also curious that if there is an ionic solution (brake fluid or dirty water) in contact with both screws with an electric potential between them, there might be some galvanic corrosion going on.

 

[2001LC]

I guess that if brake fluid gets in there, a small hole would let that drain as well?

I'm also curious that if there is an ionic solution (brake fluid or dirty water) in contact with both screws with an electric potential between them, there might be some galvanic corrosion going on.

I think you've a good point, it's very likely.

 

[DallasDog]

Following closely. Checked my reservoir today as I had the system flushed a couple of weeks ago when taking care of other dealer service. It is above the max fill line.

 

[CloudCity]

I got a response from the dealership, they are going to replace the brake master assembly for $4275. ouch....

I did request to save all of the old parts and will report back when I have news.

That is so much higher than I paid at Kuni Lexus in Beaverton, OR when I had my brake assembly replaced last summer. They billed me $2,894.90 after I requested a discount from the original $3,279, which is still $1,000 less than you were quoted.
I do also know that almost every dealership has service specials so check that page when you take a vehicle in especially for high dollar work, and most Toyota shops even have something along the lines of a high-mileage discount so I usually get 15% off any service at very least. @2001LC even mentioned this normally running $4-5k, I wonder why the huge price difference?

This is speculation but some dealers really just toss a price out there to see if it sticks. I had a buddy who took his wife's Toyota van for service and they told him it would be $300 for a particular service (I don't recall what) but when he balked at the price they said, "ok, $99 then?" so he had it done. That's just shady AF if you ask me.

 

[Amplificus]

After the repair was completed, they said they would lower the price a bit to $3995. I was at their mercy since I was not really wanting to drive a vehicle with no brakes while shopping around. I use it for deliveries and customer visits so I really just needed it fixed.

This was a dealership in Orange county where prices for luxury items (Lexus being one of them) are really getting jacked up due to some international influence. I am sure if I were to take it to another area (almost ANY other area) it could have been cheaper. The price was right in range of what @2001LC said.

 

[CloudCity]

After the repair was completed, they said they would lower the price a bit to $3995. I was at their mercy since I was not really wanting to drive a vehicle with no brakes while shopping around. I use it for deliveries and customer visits so I really just needed it fixed.

This was a dealership in Orange county where prices for luxury items (Lexus being one of them) are really getting jacked up due to some international influence. I am sure if I were to take it to another area (almost ANY other area) it could have been cheaper. The price was right in range of what @2001LC said.

I used to live in Hollywood area so that does make sense, and more so for OC. I've just learned to always ask for a discount and I've never been turned down but I'm glad you were able to save a little bit of scratch. The good news is it should last another 15-years!

 

[kruisinkid]

@2001LC what is the p/n for the booster motor wire? my 12/99 (model year 2000) LC on partsouq gives a p/n that is NLA. 8963930100 seems to be dead? thanks! im at 220k miles and brakes are fine so far. but have a couple long trips planned this summer and want to get ahead of it.

 

[2001LC]

After the repair was completed, they said they would lower the price a bit to $3995. I was at their mercy since I was not really wanting to drive a vehicle with no brakes while shopping around. I use it for deliveries and customer visits so I really just needed it fixed.

This was a dealership in Orange county where prices for luxury items (Lexus being one of them) are really getting jacked up due to some international influence. I am sure if I were to take it to another area (almost ANY other area) it could have been cheaper. The price was right in range of what @2001LC said.

After inspecting the brake Master assembly you supplied me for testing. I found motor dead just as I thought I would.

Observed booster motor wire was slightly corroded at bottom of ABS unit only, other end of wire at motor was clean. I first tested from wire at leads under ABS where corroded. Jumping to a good 12V battery, nothing happen! I then jumped to the leads directly on motor to eliminate wire. Motor spun (ran). I then tried again and nothing worked. This indicated a dead spot. Dismantled the motor and found dead spot on commutator.

@2001LC what is the p/n for the booster motor wire? my 12/99 (model year 2000) LC on partsouq gives a p/n that is NLA. 8963930100 seems to be dead? thanks! im at 220k miles and brakes are fine so far. but have a couple long trips planned this summer and want to get ahead of it.

I've been sending partsouq.com daily emails with list of parts not available or not found! I'll add this one brake master booster motor wire 89639-30100 too it. But doubt it will help. Googled and found in the $200 range. I'm going to see if the have the motor or booster assembly . It includes wire!

 

[kruisinkid]

The motor is available on ebay i saw. About 700 shipped to the US from UK