Poll on total brake failure in 100 series (3 Viewers)

[Amplificus]

Wow that's interesting about the wear on the motor commutator, i don't see how a shorted electrical connector would cause that, is it possible that the corrosion was attacking the brushes and commutator too? I have seen wear like that on old rc car motors but normally sand/dust were involved

 

[MUDZLLA]

Yep I had TBF on my 1998. Pumped like s*** and seemed to come back, enough to keep me from going over the side of a mountain road. Replaced the motor and pump with OEM off ebay. Better but still losing pressure so pulled the master and did the plunger. Still better but now the pump is running too often and fluid leaks back to the reservoir after sitting a few days. Guessing its the accumulator check valve. Funny thing is an accumulator check valve appeared on my work bench a few weeks after my plunger swap and damned if I know where it came from... Oh yeah the plunger did have a bad O-ring. Anyway does anyone know if it takes days for pressure/fluid to drain back to the reservoir with a missing accumulator check?

 

[2001LC]

Wow that's interesting about the wear on the motor commutator, i don't see how a shorted electrical connector would cause that, is it possible that the corrosion was attacking the brushes and commutator too? I have seen wear like that on old rc car motors but normally sand/dust were involved

Need and electrical engineer to step in here, and explain why. I have read this: "Less Voltage ( or Under-voltage) gives rise to more current drawn, thus producing more copper losses (I^2 R) " So would a change in resistance of the resistance wires effect voltage. I'm thinking the answer is yes!

The motor body is very well sealed from sand and dust. The motor has a cork or paper type seal between it and pump, and metal seal between it's body and face plate. It certainly possible for fluid to get into motor thru metal seal. I would think if it did, the spinning motion of motor would force fluid off commutator. Any fluid that did get on commutator and brushes, may also act as lube and cleaning fluid.

I've yet to see any of the brushes worn out as they're very long, having more depth (copper) than the commutator. So the commutator seems the weak link.

But it must be noted here, that how often motor is activated (started up) and how long it runs makes the biggest difference. Some that rides the brakes, drives in heavy stop and go traffic or brake system that has a leak all would cause motor to run more. So mileage is not a good indicator. How many miles between Brake pad jobs may be a better indicator.

I've a 00LX with more 350K miles. No sign of corrosion on wires and motor (according to vehicle history) is the factory installed. It's had many brake jobs from what I can tell (missing first 2 yrs & 100K mile of history)

I guessed! your wires would have some corrosion, hey did. Although not much, and screws came out without drilling them out. Usually I've had to drill them out due to corrosion. So your corrosion was mild.

But my guess was based on the fact, I've only repaired master brake ABS & motors, that wires had corrosion on them. I've also seen some in mud document failure, which included corroded wires. I hope more will come forward with detail and or ship Master to me for inspection.

This is not to say a motor won't fail ever with good wires, it will. It just that I'm only seeing bad wires on failures to date.

My first brake master repair was not a failed motor. It was the ABS unit failure. It was first time I noticed the wire corrosion. I suspect the corrosion of wire may have had some affected here as well. As the current passes through the ABS unit. I've not yet tested your ABS, as only way I've to do this is by hooking to a vehicle. The tech stream will give DTC if ABS bad. Since your narrative did not included CEL prior to any brake issue, I doubt ABS bad. When ABS fails, we can still drive in most cases as long as we still have normal pedal pressure. It is possible for s short in ABS then not getting power to motor I suppose. As FSM has us test first by jump 12V to ABS, the directly to wires at bottom, the directly to motor.

The pump could also be weak. But I've yet to see one go bad. However, and old pump would presumable produce less pump pressure (fluid flow) due to internal wear. This may also cause longer run time of motor. This may, in part, be why we get a range in the timing of accumulator "run time" test of 30-40 seconds. But still this would not make a lot of difference to motor. Provided motor running at stated voltage & amperage. Motor starting and stopping often, tend to fail sooner than continuous running motor. My understanding, is the sudden power surge is hard on the motor. That once running with steady power source it will run with less wear.

Accumulator cylinder also can fail. But I've yet to see one fail.

I'm hoping more like you @Amplificus will ship me their Master Brake Assembles for inspection. Thank you so much for contributing to the date bases. Picking up shipping was very classy on your part.

It's only anecdotal evidence at this point, that wire is a clue to early failure. The more master I inspect, the more credible and valuable the date bases will become. At this point I do feel it is a sign, that wire need inspecting. One that should not be ignored!

The reason for the wires corrode is also just anecdotal evidence. I find wires corroded in overfilled reservoirs and ones not overfilled at time of my inspection. So this will never know why. As It only needs be overfilled once in it's history to over flow and get into boot(s).

The pile of dust seen coming out of motor housing, should be a copper dust from commutator and bushes. Commutator would spin off dust, so should not add much effect on wear as and abrasive.

I do know that in every case, where I've pulled the motor apart and found commutator worm out, wire had some corrosion.

 

[hickuptruck]

Wish Toyota was like Mercedes and warrantied these for 25 years unlimited mileage. Mercedes had problems with these SBC units that are much like the units 100s have. Recalled about 1.5m of them, and then they went back to hydraulic instead of electro-hydraulic. Same design units are in the Prius and they got recalled and a 10yr 150k mi warranty because enough people were complaining to NHTSA of tbf that Toyota had to step in.

Question: I have no codes on TIS but my booster motor kicks in, and loud every 2-3 pedal pumps. Can hear it clearly behind the dash inside. It's a rebuilt eBay unit. It does run in 30-40 second range on startup though. Is this within spec? Wonder if my accumulator o ring is shot, or the valve is bad, or if the accumulator is bad. Might consider buying a new accumulator for $350 but I don't want to throw parts at it.

 

[bentonrover]

Just thinking here? Not sure if someone else have asked this. So what is the census of failures of city to non city driving? You have failures at 80k and none at 300k miles. Like is there more fails in like LA, NY or Houston? Compared to Vermount or Colorado type of drives. Just some examples of wear and tear for brake components.

 

[2001LC]

Wish Toyota was like Mercedes and warrantied these for 25 years unlimited mileage. Mercedes had problems with these SBC units that are much like the units 100s have. Recalled about 1.5m of them, and then they went back to hydraulic instead of electro-hydraulic. Same design units are in the Prius and they got recalled and a 10yr 150k mi warranty because enough people were complaining to NHTSA of tbf that Toyota had to step in.

Question: I have no codes on TIS but my booster motor kicks in, and loud every 2-3 pedal pumps. Can hear it clearly behind the dash inside. It's a rebuilt eBay unit. It does run in 30-40 second range on startup though. Is this within spec? Wonder if my accumulator o ring is shot, or the valve is bad, or if the accumulator is bad. Might consider buying a new accumulator for $350 but I don't want to throw parts at it.

Sound normal.

 

[1NTRANSIT]

@2001LC Major thanks for the info you’ve provided us in this thread!

I kept my head burried in the sand and avoided this thread for quite some time...glad I finally reviewed this week. I found a badly corroded connection on my 04 LX w/139k.

My concern now is that the pump motor could still be set to fail even if I replace the cable. Am I wiser to just go ahead and replace the entire motor assembly? I wouldnt know what I was looking at in terms of motor condition if I tore it open.

I have a cross country trek planned this summer and am inclined to take the fix before its broke approach.

 

[2001LC]

@2001LC Major thanks for the info you’ve provided us in this thread!

I kept my head burried in the sand and avoided this thread for quite some time...glad I finally reviewed this week. I found a badly corroded connection on my 04 LX w/139k.

My concern now is that the pump motor could still be set to fail even if I replace the cable. Am I wiser to just go ahead and replace the entire motor assembly? I wouldnt know what I was looking at in terms of motor condition if I tore it open.

I have a cross country trek planned this summer and am inclined to take the fix before its broke approach.

TBC: I did not start this thread.

I suppose it's helpful thread, but I do fear it is scaring people needlessly that the 100 series has a defect, it does not. It's one of the most over engineered and safest vehicle on the road.

This electric motor set-up is in every Toyota SUV or truck I've looked under the hood. The threads starts out making 100 series owners thinking this is some kind of 100 series issue from a defect, it's not IMHO.
@1NTRANSIT
Best would be replace the motor or the booster assembly, which wire comes with either. My approach, going forward, will be R&R corroded wire and to pull the motor apart and inspect/rebuild. If commutator to worn out, I'll replace motor also.

If (BIG IF) I am right. IN that:
1) Brake fluid is getting in wires boost from over filling reservoir.
2) That this then leads to corrosion of resistance wires and fasteners.
3) That the increase resistance then leads to commutator wearing out prematurely.

Then some research on Toyota's part my be in order. IF I'm right: We need to a TSB from Toyota warning of this and adding inspect wire to PM at minimum. I've asked SM at Dealership about the wire. They just give me a blank look and say NO! I'll ask around in the shop. But these shop mechanic don't take these brake master apart. They just replace the whole assemble and toss the old one.

In Toyota's defense, they tells us; Do NOT offer fill reservoir. They also went the extra miles and embossed instruction on the reservoir. So they've no liability that I can see. But I'm not a lawyer!

Where I'd love to see Toyota buy us all new master assemblies. I just don't see it happening. The issue is not sudden and without warning. It just most ignore the alarm and lights. Fluid 1mm below the low line we'll get and alarm. Alarm or lights should never be ignored. If alarm broken we still "should" see brake lights on dash.

 

[FxFormat]

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.
View attachment 1952874

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!

Okay you guys got me nervous and i checked my connection on the bottom, it looks to be flaking a bit but not rusted through like the pic. What can i do without removing the assembly and cleaning the connector and putting it back on. Seems like a lot of work, can i just throw some grease in there and put it back on so it doens't rust further, or fluid film perhaps?

 

[2001LC]

If not bad. Try an electric contact cleaner safe on plastic. Then fill the boot with a electric contact grease safe on rubber and plastic. Get boot back on tight and do not ever over fill brake reservoir.

Just because wire corroded doesn't mean you booster motor will fail tomorrow. My thinking is, it reduce life of motor. How often the motor run still would have the biggest effect.

Doesn't hurt to make sure E-brake in good working order. I just put in new shoes on Emerald, my 00 w/350K. I've also flushed the brake fluid. Rebuilt the calipers. Next I'll inspect all hard lines, flexible lines inspected and are okay.

Make sure dash lights work and alarm!

 

[2001LC]

I've put drain holes in some, filled some boots and both to others. Both on and off the rig.

Replaced screws, nuts & wires

 

[2001LC]

Please anyone with any brake master parts, I'm interested in them. PM me and will work out something.

The more master assembles I pull apart and inspect, the better my data base will be. The goal here is to give as good advice as I can, for inspecting for clues that may indicate a failure before hand.

The more of these I tear apart. The more patterns will come to light! Right now it's the wire and the commutator of the booster motor.

I'm also thinking there made be a correlation to ABS unit and wire. But to date, I've only had one of those to inspect.

Also looking at master plunger, pump, pressure switch and accumulator.

 

[abuck99]

Okay you guys got me nervous and i checked my connection on the bottom, it looks to be flaking a bit but not rusted through like the pic. What can i do without removing the assembly and cleaning the connector and putting it back on. Seems like a lot of work, can i just throw some grease in there and put it back on so it doens't rust further, or fluid film perhaps?

I disconnected battery and used a portable Dremel with a wire brush attachment to gently clean away the surface crust from the connectors/screws then coated with dielectric grease.

 

[FxFormat]

I disconnected battery and used a portable Dremel with a wire brush attachment to gently clean away the surface crust from the connectors/screws then coated with dielectric grease.

really tight fit down there but i gotta do this so i dont end up with problems in the future

 

[abuck99]

really tight fit down there but i gotta do this so i dont end up with problems in the future

Yeah awkward angles and such but if you have a Dremel or mini wire brush it helps expedite

 

[1NTRANSIT]

@abuck99 did you fully disconnect the screws prior to the dremel job? I fear my screws are going to be seized up so may need to hit them with some PB blaster over a couple of days. Any concern with PB corroding the plastic on the ABS unit?

 

[abuck99]

@abuck99 did you fully disconnect the screws prior to the dremel job? I fear my screws are going to be seized up so may need to hit them with some PB blaster over a couple of days. Any concern with PB corroding the plastic on the ABS unit?

No I did not remove screws- I had the same worry and left them connected. I just polished the crust off the screws, cleaned up the area and greased with dielectric. I would not use any solvent/pentrant in that area as the capillary action might suck the chemical into the resistor wire and cause some unforeseen issues.

 

[FxFormat]

I'm not sure why Toyota decided it was a good idea to put a bowl underneath the connectors and trap all the water/salt/brake fluid there.

 

[2001LC]

If screws are frozen, corrosion has gone to far. I strongly suggest you pull the master assembly and carefully drill out wires/screws. Take care not to break plastic.

Replace: wires w/boots, screws and nuts with new OEM is best practice. You can inspect commutator of booster motor at this time.

 

[1NTRANSIT]

No I did not remove screws- I had the same worry and left them connected. I just polished the crust off the screws, cleaned up the area and greased with dielectric. I would not use any solvent/pentrant in that area as the capillary action might suck the chemical into the resistor wire and cause some unforeseen issues.

Thanks and good call on the PB.

If screws are frozen, corrosion has gone to far. I strongly suggest you pull the master assembly and carefully drill out wires/screws. Take care not to break plastic.

Replace: wires w/boots, screws and nuts with new OEM is best practice. You can inspect commutator of booster motor at this time.

Im going to try to loosen the screws tonight and see what happens. If frozen I'll pull the MC.

I'll tear down the motor if the MC gets pulled, are there any tell tale signs that a commutator is on the way out? I've seen your pics showing dead spots on a comm however mine is still running so it may not be as obvious.