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

[Poncherelli]

Just for reference could this be from not b

This is concerning "Brake Booster Pump Motor on Time Abnormally Long". We never want to see this. Motor running longer than 2 minutes cause excessive wear.

This "Open ABS solenoid relay" could be key.

What is junction? "so I now replaced all brake lines, junctions and put a new pump motor.
Was that a new OEM motor & pump and with new brake control wire?

The junction is the metal housing all the hard brake lines go into from the master cylinder heading out to the wheels (where they then split off to the rear and front wheels)

I replaced motor only and brake control wire.

I did talk with someone who said I need to clear the codes after the repair with an ABS scan tool. They said the codes might not go away on their own.

Any thoughts? I don’t want to throw parts at it...but maybe I need to?

 

[2001LC]

I sorry I thought you cleared the codes and they came back. For sure clear the codes!

 

[Poncherelli]

I sorry I thought you cleared the codes and they came back. For sure clear the codes!

I guess I’m saying I thought I cleared them...but now I see it wasn’t with an ABS reader...so I think I never cleared them.

 

[2001LC]

You don't need and ABS reader. "Most" typical reads will clear all codes.

Clear, than look to see that no codes remain.

 

[Adski]

New member to the forum here. And unfortunately a new member of the total brake failure club. 99 Land Cruiser with 240K mi. My daughter was driving when the ABS light and buzzer started going off. She was a few blocks from home when it happened, neighborhood driving. She got it home and could barely stop it in the driveway. Brake pedal does not sink to floor, but is fairly hard instead. No stopping power at all.

Towed to reputable Landcruiser shop in Midvale, UT and was diagnosed with needing full ABS assembly, between $3-4K for MC, accumulator, pump, etc. I am not a DIY-er on trucks, and after watching and reading some here, I see it's a pretty big job to replace all the necessary parts.

Question now is: pay to repair or sell the truck? Had this rig for 8 years now. Mini-wrecked it and insurance totaled it, paid me out and I bought it back from them and drove it another 2 years. Strong motor, but may be someone else's turn to enjoy this one

 

[johnnyquest]

Curious if that’s what I’m experiencing. How did you know the abs was activating? Was it from vibration in the brake pedal?

Currently I’m annoyed that I feel vibrations in the pedal but as far as I can tell the vibration is tied to when the motor runs. Is that normal?? I’m running by Toyota today to see if the code came back after I cleared it.

The abs would activate sometimes during, but more disturbingly after braking. A little at first and then later more vigorously. Activetrack light would flash on dash.

For me the fix (after doing the MC, accumulator and pump) was the front speed sensors. I purchased rear sensors in case that didn't solve it and they are yet to be installed.

In this thread the culprit was the steering rack and bushings:

lx470 the vsc warning light goes on

On my 2000 Lexus lx470 the vsc warning light goes on, sounds a very loud beep and brakes are applied hard on freeway at 50 mph in a long sweeping left turn. Speed limit on this freeway is 70. the car dive hard to left and scares the @!$#$ out of me when it happens. it is now increasing in...

forum.ih8mud.com

My steering rack and bushings were fine.

One guy changed his front tires and it fixed the problem.

Indications in both these instances pointed to one side slipping more than the other, in turn causing the speed sensor to trip.

Check tires and rack before sensors...

 

[CloudCity]

Question now is: pay to repair or sell the truck? Had this rig for 8 years now. Mini-wrecked it and insurance totaled it, paid me out and I bought it back from them and drove it another 2 years. Strong motor, but may be someone else's turn to enjoy this one

I know it's a big bite but I'd fix it. Some folks have had luck with replacing individual rebuilt parts, tho I went with a whole new assembly. I think you won't get much for a truck that has major brake issues, and you can't really sell it without disclosing that, so I'd repair it and keep driving until it needs the work done in another quarter of a million miles.

 

[montegofd3s]

Flush the system bleed the hell out of it, activate ABS via dirt road/field, bleed, activate abs, bleed), and extend the master cylinder plunger on the back of the pedal so the pedal engages higher. Try that first before anything.

 

[CloudCity]

extend the master cylinder plunger on the back of the pedal so the pedal engages higher.

How do you do that, in the footwell area? My brake has a slight amount of dead space before it gets resistance, maybe 1/2' so not a major deal but I like things to have closer tolerances if it's an easy fix. Thanks much!

 

[Poncherelli]

Flush the system bleed the hell out of it, activate ABS via dirt road/field, bleed, activate abs, bleed), and extend the master cylinder plunger on the back of the pedal so the pedal engages higher. Try that first before anything.

Can you explain extending the master cylinder plunger so the pedal engages higher?

 

[Poncherelli]

Maybe crazy thought...but to add to this discussion , I believe running worn brake pads may result in master cylinder / pump issues in the long term.

Reason being, I have felt quite a bit of pump motor feedback when running, and experienced the pump running what I thought was too frequently. Changed pump for a new one but didn’t run any less frequently just more smoothly and quieter.

Then decided to take rear brakes apart and saw really low pads that my shop had said weren’t horrible. They were. One was almost at the metal. I replaced pads and rotors. Now pump runs less frequently and much smoother to where I don’t feel the feedback from the motor when running nearly at all.

Someone who understands how this systems works much better than I do could possibly explain what I’m sensing more eloquently but thought I’d add this to the discussion.

 

[GXO]

Maybe crazy thought...but to add to this discussion , I believe running worn brake pads may result in master cylinder / pump issues in the long term.

Reason being, I have felt quite a bit of pump motor feedback when running, and experienced the pump running what I thought was too frequently. Changed pump for a new one but didn’t run any less frequently just more smoothly and quieter.

Then decided to take rear brakes apart and saw really low pads that my shop had said weren’t horrible. They were. One was almost at the metal. I replaced pads and rotors. Now pump runs less frequently and much smoother to where I don’t feel the feedback from the motor when running nearly at all.

Someone who understands how this systems works much better than I do could possibly explain what I’m sensing more eloquently but thought I’d add this to the discussion.

Makes sense to me as the pistons have to travel further and push more fluid.

 

[2001LC]

Piston(s) don't actually need to travel further. They travel very little at any time, new or old pads. When pads are worm fluid level drops in relation to wear. That is because piston are now extend further at all times. The pads back off the rotors only microns, new or worn, as brake pedal released. The pistons do not retract to a fixed staring point.

I can think of few reasons run time would be less after pads & rotors. One being: Caliper piston(s) pitting. Seal is retained in caliper at a fixed point. Piston sides in and out on seal. As new pads installed, piston may be in better spot (without pitting) created a better seal.

 

[bentonrover]

Maybe crazy thought...but to add to this discussion , I believe running worn brake pads may result in master cylinder / pump issues in the long term.

Reason being, I have felt quite a bit of pump motor feedback when running, and experienced the pump running what I thought was too frequently. Changed pump for a new one but didn’t run any less frequently just more smoothly and quieter.

Then decided to take rear brakes apart and saw really low pads that my shop had said weren’t horrible. They were. One was almost at the metal. I replaced pads and rotors. Now pump runs less frequently and much smoother to where I don’t feel the feedback from the motor when running nearly at all.

Someone who understands how this systems works much better than I do could possibly explain what I’m sensing more eloquently but thought I’d add this to the discussion.

I always said the same thing

 

[2001LC]

IMHO That is sign the brake caliper piston have pitting. What happens is; As we replace the pads. Now the pistons are pushed back to full compression. This put cleans surface of piston back of seal. This is a sure sign brake flushing was not done regularly. It's the build up of moisture in old brake fluid pitting the piston. Piston move outward (toward rotor disk) as pads wear, surface area that was expose to old fluid the longest now comes in contact with the seal.

Note: When we flush and bleed. We are not getting all the old fluid out of the calipers. This is one more reason to flush often.

These seal are also 20 years old. They shrink and wear just a bit. Actually amazing to me, how long they last. Exposed to cold they shrink a little more. I was just speaking to a master diagnostician at Toyota Dealership on this. They see brake alarms & lights coming on and then going off, all the time in cold weather due to cold seal shrinkage. As we work/use the brakes, seals warm up (expand) and pressure comes back to acceptable range.

I'll bet inspecting pistons of caliper where booster run time is reduces with new pads install. They will not be serviceable based on FSM standard.

 

[Poncherelli]

IMHO That is sign the brake caliper piston have pitting. What happens is; As we replace the pads. Now the pistons are pushed back to full compression. This put cleans surface of piston back of seal. This is a sure sign brake flushing was not done regularly. It's the build up of moisture in old brake fluid pitting the piston. Piston move outward (toward rotor disk) as pads wear, surface area that was expose to old fluid the longest now comes in contact with the seal.

Note: When we flush and bleed. We are not getting all the old fluid out of the calipers. This is one more reason to flush often.

These seal are also 20 years old. They shrink and wear just a bit. Actually amazing to me, how long they last. Exposed to cold they shrink a little more. I was just speaking to a master diagnostician at Toyota Dealership on this. They see brake alarms & lights coming on and then going off, all the time in cold weather due to cold seal shrinkage. As we work/use the brakes, seals warm up (expand) and pressure comes back to acceptable range.

I'll bet inspecting pistons of caliper where booster run time is reduces with new pads install. They will not be serviceable based on FSM standard.

Thanks. That seems to be the consensus on what I’m experiencing. I will add then to this conversation that not only should the master cylinder / pump / actuator be serviced when the ABS Brake light alarm comes on, but also the calipers. Lucky for us it seems that calipers can be purchased for around $50 each...and is perhaps well worth it when servicing the ABS brake light issues we deal with.

it’s also a chicken or egg situation...did bad calipers lead to overworked motorand subsequent failure? Or did it just expose a motor that was at the end of life?

 

[2001LC]

What caliper are you getting for $50?

 

[Poncherelli]

A few rebuilt versions

What caliper are you getting for $50?

Rock auto has dozens of options for less than $40

 

[GXO]

Interesting data point: I upgraded my GX470 (same MC as the 100) to a big brake kit front and rear. The tolerance for piston movement is MUCH smaller throw. I see a lot less fluid movement, more pedal pressure, and the MC doesn't prime at all anymore.

 

[Poncherelli]

Interesting data point: I upgraded my GX470 (same MC as the 100) to a big brake kit front and rear. The tolerance for piston movement is MUCH smaller throw. I see a lot less fluid movement, more pedal pressure, and the MC doesn't prime at all anymore.

View attachment 2170608

View attachment 2170609

Show off.