Brakes ...... Overdue write-up on brakes. (1 Viewer)

Joined
Nov 4, 2007
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First and foremost: Brakes should only be worked by those with high level of mechanical abilities and experienced with brake systems.

My hope is below link will give better understanding as to what we can do to reduce brake failure and what to watch for. The info is from my experiences and my thinking as to what and why brakes fail on 100 and 200 series. As such, is subject to change, as I learn and others contribute!

IMHO most brake failures are preventable, in the relative shorter term.

It's difficult to define short term. As brake usage in a perfectly health brake system, is so varied. As some are constantly on brake pedal ever few feet (stop and go traffic). Whereas others may go ~200 or more miles without touching pedal on regular basis (HWY vehicle). The 1 million mile Toyota had no brake issues reported IIRC.

It is sudden zero pressure in brake master and lines, that yields pedal to the floor, which results in relatively no usable brakes. This happens from lose of fluid or brake booster pump motor failure.

Eventually all brake booster motor will fail in all motorized brake systems. It's the motor failing to start/run that yields zero pedal more than anything else I've seen. As the motor turns the pump, pressurizing the accumulator.

A few tips:

First:
Never ignore brake warning lights or alarms.

Second:
After vehicle has sat with IG key off, for a few hours. The pressure in brake system bleeds down. The older the system the faster it bleeds down, primarily do to aging of a rubber seal or seals and depletion of nitrogen gas from accumulator. By turning the IG key to ON, the booster motor will activate once pressure sensors senses pressure below a preset level.

By listening before starting engine, brake booster motor can be heard running. Motor not running or run for more than 40 seconds or is a warning. If not heard, press brake pedal a few times, it should than be heard, since pressing brake pedal depletes stored pressure from accumulator. If motor takes all of 40 second run time before stopping most times, or even just when vehicle key off (no power to motor) for short periods, that should be investigated.

Third:
Periodically test booster motor run time. Do this by pumping brake pedal 40 times with IG key off or key out of IG. Than check level in brake master fluid reservoir. Which should be at or near max line but not over. Than turn IG key to ON, and time booster motor run time. 40 seconds is max. 28 second is a very health system (new or newer). 40 seconds is limit, but may indicate some weakness. i.e low voltage/amp from battery, weak seals, bad fluid, etc. Over 40 second, service is necessary.

Prevent measures.
  1. Flush brake fluid often. No longer time period between flushes than 3 years, after first factory fluid flushed out.
  2. I've gone back to using only Toyota brake fluid. It's pricey and may not make any difference. Toyota no-longer states on bottle who makes. But the extra cost worth it for piece of mind. Toyota stated on the bottle "engineered to Toyota spec", may help protect seals in system. Condition of seal is very important to heath. of master. Bad seals can weep or even squeal under high pressure. Booster motor will then run excessively, as pressure keeps dropping.
  3. Inspect motor run time and listen for excessive running of motor.
  4. Never overfill brake fluid reservoir. Fluid may escape from cap or grommets at bottom. If fluid get on booster motor brake control wires, it may enter boots protecting wires at connection points under boots. The ensuing corrosion from hygroscopic action, will increase resistance of brake control wires. This will hasten motors failure, very rapidly. Brake fluid may also get into breather port for motor. The moisture will attack dust. This may clog breather and then as motor creates a vacuum (high RPM spin) it will suck fluid from pump into motor.
  5. Inspect breather at bottom of booster motor annually. Deep water crossings, driving in tall grasses, muck, very dusty condition, missing fender or undercarriage shielding, lifted increasing opening area in fender to engine bay, oversize tires, etc. May all add to debris entering engine compartment. Be on the watch and check breather more often under these or extreme driving condition. Or ensuing fluid sucked into motor from pump, will damage brake booster motor.
  6. Keep battery, battery post clamps and cables properly serviced. Volt/Amp drop from battery, will be the same as increased resistance in wires. This will also effects RPM (slowing) motor.
  7. Keep grounds to frame, body and engine properly serviced.
Hope above helps. Be safe!


Brake failure:

Brake booster motor failure, is number one reason for no brakes!

I'll start with the most common cause of brake failure. Loss of brake system booster pressure.

Other than no brake fluid in system, which one can easily see. Brake booster motor failure, is number one reason for no brakes.

These are just my opinions I drew from working on 100 series brake systems. Many, muds members help me gain understanding on the subject. Some with their posting in mus, others by sending their failed master to me, to dissect. Thanks all of you :cheers:

Overfilling brake fluid reservoir, "may" cause loss of brakes:
IMHO this is number one reason for sudden brake failure.

Over filling; Such a small thing, most Toyota Master ASE certified mechanics, will say makes no difference. Most are not even aware; Toyota embossed instruction on topping on the brake reservoir. Even spillage on reservoir can have same effect.

If brake fluid aloud to run down side of reservoir. Fluid may get on the wires and/or into its sheathing. Fluid may then travels down the wire(s) into the boots.

Brake fluid is hygroscopic (pulls moisture from the air). If brake fluid gets in the boots of the brake control wires, which are resistance wires. The wire terminals, nuts & screws will corrode from moisture in fluid. This corrosion will increase resistance of wires, causing the commutator to prematurely wear out. IMHO: This is leading cause of motor failure.

Overfilled brake reservoir or fluid spillage, effect on wires, seen below.
3 Wires ABS unit 3-15-18.JPG



A second cause for brake booster motor failure. Is excessive long run times:

Motor running excessively long, each time it is called (pressure in system low) on to run. This happens most often due to a leak or air in system. Leak is not always external (internal pressure leak). Internal pressure leak, will not cause fluid level to drop. Note: level drops naturally with pad wear. I'll touch on this subject later. But if we hear the screeching sound when motors is running and may see bubbles (wake in fluid seen) come up front of reservoir. This is internal pressure lose. The master will need replacing, or pump will run excessively long. Pump is designed for short run time. Running to long each cycle, can overheat the motor. This (heat) too cause premature wear of motor.

A third cause for motor failure.
Brake fluid, gets in the motor from passive seal in the pump, which is not a pressure seal. It's the seal seen when motor pulled off the pump.

What happens is the motor air vent become clogged. The pump has weep drain canal on face of pump, where motor mounts to it. The pump also has a air vent with boot cover next to the drain canal The motor's mounting face plate, has an air vent hole leading to this air vent boot. This air vent is designed to reduce the vacuum (negative air pressure), built up inside motor, as it spins at high RPM. If the air vent gets clogged, brake fluid is then sucked from passive seal weep area of pump, into motor. If weep canal drain is also clogged, it suck brake fluid out past passive seal from the pump. The brake fluid then soaks/damages the rubber insulation in the motor. This brake fluid can also damage motor bearings. It "may" also affect resistance within motor, by affecting contact between brushed and commutator and or windings IDK.

Pump and motor with clogged vent pictures:

Pump (side motor attaches to)
016.JPG


Motor
015.JPG

Motor & Pump
010c.jpg

008c.jpg
 
Last edited:
Joined
Nov 4, 2007
Messages
10,552
Location
Colorado
Master replacement only cure, If screeching sound with bubbles!

The screeching sound with bubbles (wake seen in reservoir fluid) coming up front of reservoir. IMHO a sign, a seal in forward point of master cylinder, is damaged. The seal can no longer handle the higher pressure developed by booster system, coming up to near factory peak pressure. So brake fluid under pressure passes it. This produces the screeching sound. Wake in reservoir is the fluid escaping (passing seal) into reservoir from back (forward of vehicle) master cylinder. This seal (currently) we've no way to replace, except by replacing Master.

At first sound (screech) for short burst and mostly when cold. As day warms or brakes used, heat expansion takes place. Then sound stops. Same happens with caliper seals, when brake applied. But without the screech sound. With these caliper piston seal damage, we do we get brake alarms, that go away when seals warmed up. Brake fluid itself, gets very hot with use. So either use or hot days will increase size of seal (heat expansion). Then when cold (cold shrinkage). So issues come and goes with cold and heat.

Over time these seals with fail. They not hold pressure any longer, even hot.

Why some 100 series seals fail, yet others do not. It has to do with brake fluid condition. Proper flushing is so important a PM.
Seal failure: "May" also have to do with brake fluid brand and type.

Note:
Bubbles are not accurate or great word to use. "Wake" in reservoir fluid is probably better. IMHO this is a rapid release of fluid under very high pressure, into reservoir.

Most will not even hear the early shot burst screeching. Why, ambient sounds. Like chimes, Radio, Cabin fans. I make sure all electricals, shut down before I turn key off when parking, OM suggest this. I turn on IG key and wait for all sound (chimes & pump) to stop, then I start.
 
Last edited:
Joined
Nov 20, 2020
Messages
4
Location
Australia
I think the problem with this particular issue on these cars is that the easiest fix is a full replacement of the whole thing, but it's very expensive move, especially on 20 year old cars. I've posted this before, but it's appropriate to this thread and might help someone searching in the future with similar issues, so i'll post it again.

My HZJ105r 1999 Land Cruiser (Australian right-hand drive) started making minor sporadic vibration and noise from the brakes assembly, not sure what part, and the ABS light flickering non-uniformly/sporadically. It seems it's showing early symptoms of inevitable failure.

I haven't timed the motor/pump running, or watched for any ripples in the reservoir, but I will check this out.

My error codes are as follows:

11 - ABS Solenoid Relay Open or Short Circuit​
34 - Left rear wheel speed sensor signal malfunction​
  • Faulty Left Rear Speed Sensor
  • Left Rear Speed Sensor harness is open or shorted
  • Left Rear Speed Sensor circuit poor electrical connection
  • Left Rear Speed Sensor rotor
  • Sensor installation
  • Brake actuator (skid control ECU)
  • C0215 - Left Rear Wheel Speed Sensor Signal Malfunction
41 - Low or abnormally high Battery Voltage or Open IG1 Circuit​
54 - Pressure switch malfunction (Trouble Area: Pressure Switch (PH or PL), Pressure Switch Circuit)​
56 - Accumulator Low Pressure Malfunction (Accumulator, Pressure switch (PH or PL), Hydraulic brake booster pump motor)​

I've eyed the fuses, solenoids and contact areas, they look in perfect condition, although I haven't used a multimeter to test them.

Left rear wheel speed sensor looks okay, but it could be an issue with the alignment, I will need to remove the wheel and check the magnets and sensor are clean and aligned, and all contacts are not impeded.

The other three codes ( 41, 54, 56) may be caused by malfunctioning motor, or a combination of module failure in the ABS, perhaps cascading failures. It seems the best way to determine is professional diagnosis with proper tools and pressure testing etc, I just wonder how much this would cost. I have a feeling I will need to get a shop to look at it and test, and then make a decision under a certain amount of duress (car being stuck in the shop, parts potentially costing much more through the shop than purchasing myself).

If I could bypass the ABS system and just use the hydraulic brakes without it I would, so that I had more time to diagnose the issue, but there are 2 main ABS fuses, and some other ABS fuses, and solenoids, and I am just not sure what I would have to remove to bypass it. The Owners Manual isn't clear on this either, and there aren't any resources online showing directions to disable and bypass it.

Looking forward to any updates you do on this thread too, and really enjoy your youtube vids 2001LC/MeMy !
 
Joined
Nov 4, 2007
Messages
10,552
Location
Colorado
I think the problem with this particular issue on these cars is that the easiest fix is a full replacement of the whole thing, but it's very expensive move, especially on 20 year old cars. I've posted this before, but it's appropriate to this thread and might help someone searching in the future with similar issues, so i'll post it again.

My HZJ105r 1999 Land Cruiser (Australian right-hand drive) started making minor sporadic vibration and noise from the brakes assembly, not sure what part, and the ABS light flickering non-uniformly/sporadically. It seems it's showing early symptoms of inevitable failure.

I haven't timed the motor/pump running, or watched for any ripples in the reservoir, but I will check this out.

My error codes are as follows:

11 - ABS Solenoid Relay Open or Short Circuit​
34 - Left rear wheel speed sensor signal malfunction​
  • Faulty Left Rear Speed Sensor
  • Left Rear Speed Sensor harness is open or shorted
  • Left Rear Speed Sensor circuit poor electrical connection
  • Left Rear Speed Sensor rotor
  • Sensor installation
  • Brake actuator (skid control ECU)
  • C0215 - Left Rear Wheel Speed Sensor Signal Malfunction
41 - Low or abnormally high Battery Voltage or Open IG1 Circuit​
54 - Pressure switch malfunction (Trouble Area: Pressure Switch (PH or PL), Pressure Switch Circuit)​
56 - Accumulator Low Pressure Malfunction (Accumulator, Pressure switch (PH or PL), Hydraulic brake booster pump motor)​

I've eyed the fuses, solenoids and contact areas, they look in perfect condition, although I haven't used a multimeter to test them.

Left rear wheel speed sensor looks okay, but it could be an issue with the alignment, I will need to remove the wheel and check the magnets and sensor are clean and aligned, and all contacts are not impeded.

The other three codes ( 41, 54, 56) may be caused by malfunctioning motor, or a combination of module failure in the ABS, perhaps cascading failures. It seems the best way to determine is professional diagnosis with proper tools and pressure testing etc, I just wonder how much this would cost. I have a feeling I will need to get a shop to look at it and test, and then make a decision under a certain amount of duress (car being stuck in the shop, parts potentially costing much more through the shop than purchasing myself).

If I could bypass the ABS system and just use the hydraulic brakes without it I would, so that I had more time to diagnose the issue, but there are 2 main ABS fuses, and some other ABS fuses, and solenoids, and I am just not sure what I would have to remove to bypass it. The Owners Manual isn't clear on this either, and there aren't any resources online showing directions to disable and bypass it.

Looking forward to any updates you do on this thread too, and really enjoy your youtube vids 2001LC/MeMy !
When ABS/brake warning lights come on. You are bypassing ABS, it shuts down. At all times you are using hydraulic pressure. If brake pedal "drops to floor", you have no pressure and so no brakes. Except very minimal braking at bottom of pedal, if system has not lost it's fluid.

I don't really see a question here. But few things come to mind.
1) Even a bad battery or low voltage can effect ABS system. ABS will shut down and give warns and DTC, for most any charging, engine or transmission issue.
2) Even though a wheel speed sensors looks good, doesn't mean it is. They do go bad. FSM has very specific test.
3) Timing booster motor run time (with battery putting out 12.7 Volts minimum) can be revealing.
4) The ABS unit (black box) on master. Do sometimes go bad. This needs very specific testing.
5) Condition of brake fluid and staining inside brake reservoir, can be revealing. Not flushing regularly, has some very bad consequence. Such as damaged seals, hard lines and caliper pistons.

Taking to a Toyota or Lexus Dealership, having a master diagnosticians look at, does not mean they charge for parts and repair. It may be well worth the fees involved. But be advised; If any issue with master. They will recommend a full master replacement. At least here in USA they do. It will also depend on whom you get in the shop to look at. Unfortunately, most Toyota/Lexus mechanics don't even know Toyota sells the master plunger. As they will not touch any part on a master.
 
Last edited:
Joined
Nov 4, 2007
Messages
10,552
Location
Colorado
I posted this in "poll on total brake failure" thread. A bit repetitive but I'll post here as well.
________________________________________


IMHO most of these brake failures are preventable, in the relative shorter term.

It's difficult to define short term. As brake usage in a perfectly health brake system, is so varied. As some are constantly on brake pedal ever few feet (stop and go traffic). Whereas others may go ~200 or more miles without touching pedal on regular basis (HWY vehicle). The 1 million mile Toyota had no brake issues reported IIRC.

It is sudden zero pressure in brake master and lines, that yields pedal to the floor (relatively no usable brakes). This happens from lose of fluid or brake booster pump motor failure.

Eventually all brake booster motor will fail. It's the motor failing to start that yields zero pedal more than anything else I've seen. As the motor turns the pump, pressurizing the accumulator.


A few tips:

First, never ignore brake warning lights or alarms.

Second, after vehicle has sat for a few hours (pressure bleeds down over time, the older the system the faster it bleeds down) or more. Turn IG key to ON, than wait and listen before starting engine. You'll hear brake booster motor run for up to 40 seconds. Not hearing or hearing run time longer is a warning. If not heard, press brake pedal a few times, it should than be heard. If motor does take all of 40 second run time before stopping, that should be investigated but is considered okay to drive.

Periodically test booster motor run time. Do this by pumping brake pedal 40 times with IG key off or key out of IG. Than turn IG key to ON, and time booster motor run time. 40 seconds is max. 28 second is a very health system with new master assy, good fluid and caliper pistons and seals. 40 seconds is limit, but may indicate some weakness. i.e low voltage/amp, weak seals, bad fluid, etc. Over 40 second and service is necessary.

Prevent measures.
  1. Flush brake fluid often. No longer time period between flushes than 3 years, after first factory fluid flushed out.
  2. I've gone back to using only Toyota brake fluid. It's pricey and may not make any difference, as Toyota no-longer states on bottle who makes. But the extra cost for piece of mind, for what is stated on the bottle "engineered to Toyota spec" may help protect internal seal. If seal weep/leak under pressure, motor will run excessively.
  3. Inspect motor run time and listen for excessive running of motor.
  4. Never overfill brake fluid reservoir. Fluid may escape from cap or grommets at bottom. If fluid get on booster motor brake control wires, it may enter boots protecting wires at connection points. The ensuing corrosion from hygroscopic action, will increase resistance of brake control wires. This will hasten motors failure, very rapidly. Brake fluid may also get into breather port for motor. The moisture will attack dust. This may clog breather and then as motor creates a vacuum (high RPM spin) it will suck fluid from pump into motor.
  5. Inspect breather at bottom of booster motor annually. Deep water crossings, driving in tall grasses, muck, very dusty condition, missing fender or undercarriage shielding, lifted increase open area in fender to engine bay, oversize tires, etc. May all add to debris entering engine compartment. Be on the watch and check breather more often under these or extreme driving condition. Or ensuing fluid sucked into motor will damage brake booster motor.
  6. Keep battery, battery post and clamps properly serviced. Volt/Amp drop from battery, will be the same as increased resistance in wires. This will effects RPM (slowing) and life of all motors. The brake booster motor and fuel pump motor of the most concern.
  7. Keep grounds to frame, body and engine properly serviced.
Hope this helps. Be safe!
 
Joined
May 26, 2008
Messages
316
Location
Leduc County
My experience - for what it's worth:
- brake and ABS lights coming on intermittently
- brake, ABS and constant alarm - followed eventually by TBF (total brake failure)
- replaced motor and accumulator pump - seeemed to work for a while then TBF
- rebuilt the master with the plunger kit - again worked for a while then TBF
- took it in somewhere, mechanic said your accumulator is shot, replaced accumulator, problem fixed

Epilogue:
- started losing oil in reservoir, suspect cracked pump/valve casing
- worked as long as I kept oil in reservoir
- got it to it's final resting place and now using it for a parts truck
- no heart to fix it any more

The End
 
Joined
Nov 4, 2007
Messages
10,552
Location
Colorado
My experience - for what it's worth:
- brake and ABS lights coming on intermittently
- brake, ABS and constant alarm - followed eventually by TBF (total brake failure)
- replaced motor and accumulator pump - seeemed to work for a while then TBF
- rebuilt the master with the plunger kit - again worked for a while then TBF
- took it in somewhere, mechanic said your accumulator is shot, replaced accumulator, problem fixed

Epilogue:
- started losing oil in reservoir, suspect cracked pump/valve casing
- worked as long as I kept oil in reservoir
- got it to it's final resting place and now using it for a parts truck
- no heart to fix it any more

The End
This leaves me with so many question.


But I'll just ask one. Which year are you parting out?
 

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