Brakes ...... Overdue write-up. (13 Viewers)

[Octous]

On 8/28/2024 fully flushed brake system per instructions from @2001LC.

Got an intermittent ABS light and buzz while driving around the neighborhood on two test drives on two conssecutive days. This was possibly due to:
1. low battery voltage (I had some new lights that did a constant parasitic battery drain)
2. washing the engine bay around the ABS unit

Pulled codes found:
1. C1256 - low pressure of accumulator

Looked at live data for ABS unit and found:
1. low ignition voltage to ABS unit

Performed following
1. Charged battery
2. Removed, cleaned and reconnected all electrical connectors on ABS unit
3. Cleared codes
4. No new errors (but live data still showed low ignition voltage to ABS unit)
5. Jumped diagnostic port under hood, ABS light blinked every .25 sec indicating healthy ABS unit
6. timed brake accumulator fill after pumping brake pedal 40 times (34 sec -- within 30-40 sec Toyota spec)
See video: 1999 Land Cruiser Brake Booster · Thursday, Jul 10 ð¸ - https://photos.google.com/share/AF1QipMirFGh-D7Sf9yBbrmp3JdlXrpDH3w4nfNQZ93oGXVZCfxiLQ8j2Qv0kpQGpjsIqw?key=QUxaNkxSdEY4YnBENFYzTHAyODhXemRHeGRnR0Rn

I've now been test driving the vehicle for a couple of days and the ABS light, buzzer, code hasn't come back. I'm thinking this was due to an electrical gremlin and not an actual real issue.

I'm hoping this isn't wishful thinking so I'm hoping that @2001LC. Can check my homework .

Going to the Rubicon in two weeks and so am paranoid about everything!

 

[2001LC]

Not sure what "low voltage" in ABS tech stream is or indicating.

When battery voltage drops to low, we'll get these DTC (codes). Provided DTC do not return, booster motor runs every time pressure drops (pump pedal more than a few time, or key off pump 40 times, key off for several hours). You should be good to go.

I'm assuming fluid good, reservoir not stained badly, brake control wire not corroded.

Make sure to check all flexible lines.

 

[Octous]

Thanks for the quick response @2001LC !
I'll see if I can get a screen grab of the low voltage live data error. It was from a 3rd party scan tool (not Tech Stream) so I'm not confident it's real.

Fluid is good
Reservoir is not stained

What is the brake control wire? Do you mean the motor to brake controller connections?

 

[2001LC]

Thanks for the quick response @2001LC !
I'll see if I can get a screen grab of the low voltage live data error. It was from a 3rd party scan tool (not Tech Stream) so I'm not confident it's real.

Fluid is good
Reservoir is not stained

What is the brake control wire? Do you mean the motor to brake controller connections?
View attachment 3947965

Yes!

 

[WanderingWarrior]

Yes!

Hi Paul,
Wanted to say your posts for past two years or ownership have helped so much! Thanks!
So have no brake master issue happening. But saw your post about the corroded wires! Please check my pictures attached, before and after cleaning with electric connector cleaner and wire brush. Didn't want to use PB blaster or others bc of the wires close to it. Best i could do right now. Any other cleaning solution for the area please let me know? [Now just read an older post of your's and so glad i happened to use only electric cleaner as you stated same. I didn't have dielectric grease but will get some and fill up boots per ur instructions in other post.
Last two pictures are off of my borescope AFTER cleaning off a lot of the crap off the bolts and two wire terminals. First was sneaking in phone to see the horror. I did manage to get a lot of the corrosion off but of course could be better. Tight area. Will try to order another type of flexible brush.

Booster time at cold start and after 40 pedal test is always around 23-25 seconds. Not sure if that’s too good? Have good brake performance. But brake booster accumulator and motor were changed in 2022 per records before i bought it in 2023. Not sure why mine is so quick always? Done the testing properly.

Then when i bought it in 2023 saw big leak from unit, on black box also and down the frame when car came off transport truck after buying. Fix was the three grommets from Toyota under reservoir. Put in new toyota brake fluid only as last guy used after market. No issues since for me. No leaks. But never thought of these wires and corrosion there from the leak.

Saw your post today and was like oh man I don’t think the shop would have cleaned off the brake fluid from the abs side black box wires at bottom or the two screws their terminals go into under the rubber cap! Out of sight location.

So I went now to check after having that leak two years ago, wish i had known sooner about cleaning this wire terminal area/ screws under the rubber cap. Will try to do more later with another type of brush. Started car and drove for 10 mins and all was good with performance and motor. Hopefully cleaning that area will help it last longer. Open to any other suggestions for better cleaning or how to keep maintaining.

But also have one brand new unit on shelf (bought in 2023) as this one that is going had grommet issue and it has per records new booster motor and accumulator put in in 2022. So i never used the brand new one. I also have that rebuilt guy's unit on shelf which was not correct one! Sent me 4 runner or GX one with smaller reservoir etc when I said please make sure it has the 99 LX one. I agree with you it’s very questionable what he’s doing. Anyway to each their own.

Best course of action, keep letting it go and whenever it does go out because of wire damage change to new full unit? Hopefully brake fluid didn't travel too far up the wires and just corrosion in that area only. Guess time will tell

Will do another bleeding soon as i'm about to do brand new Toyota calipers and brakes lines and shims and pads in few days myself. Will bleed via tech stream. Calipers and new things coming on because 1999 with 297,000 miles and I have good brakes (10mm) except for a squeal that comes from only driver side tire area (not booster area, checked many times) and comes only after many hours of driving. This began a 6 weeks ago after doing some hill driving for few weekends in a row. Now comes every few days after hours of driving and often in traffic. I am using engine braking.
Cleaned it, applied toyota proper grease with current setup, calipers seem harder than they should be to push in (do go in) but when testing some do not come out as easy as others. So with a sale figured i change everything. Rotors still look very good according to toyota and other mechanics. I will change this stuff out myself. Sorry for going off tangent but sort of related as i will be doing the tech stream bleeding. If rotors need to be changed after i change everything else in the area with toyota calipers, brake hoses, pads, shim kit etc, i will then redo the hubs and bearing job that did in December.

 

[2001LC]

Hi Paul,
Wanted to say your posts for past two years or ownership have helped so much! Thanks!
So have no brake master issue happening. But saw your post about the corroded wires! Please check my pictures attached, before and after cleaning with electric connector cleaner and wire brush. Didn't want to use PB blaster or others bc of the wires close to it. Best i could do right now. Any other cleaning solution for the area please let me know? [Now just read an older post of your's and so glad i happened to use only electric cleaner as you stated same. I didn't have dielectric grease but will get some and fill up boots per ur instructions in other post.
Last two pictures are off of my borescope AFTER cleaning off a lot of the crap off the bolts and two wire terminals. First was sneaking in phone to see the horror. I did manage to get a lot of the corrosion off but of course could be better. Tight area. Will try to order another type of flexible brush.

Cleaning, drying and packing wire boots with grease. Slow the corrosion, buying some time. But the resistance has already changed (increased) in wires. How much and for how long, and it's affected the motors commutator, IDK.

You can replace wire (brake control wire w/boots), screws and nuts. At same time inspec motors brushes and commutator.
Note: I've see Toyota parts retail counter. Charge as much as $350, just for the wire. It can be found for much less. I keep a few used and new in stock.

Booster time at cold start and after 40 pedal test is always around 23-25 seconds. Not sure if that’s too good? Have good brake performance. But brake booster accumulator and motor were changed in 2022 per records before i bought it in 2023. Not sure why mine is so quick always? Done the testing properly.

23-25 sec is like new. Indicates good motor getting very strong battery voltage, good accumulator and good heavy brake fluid void of air. Also indicates system holding pressure well (no leaks).

Then when i bought it in 2023 saw big leak from unit, on black box also and down the frame when car came off transport truck after buying. Fix was the three grommets from Toyota under reservoir. Put in new toyota brake fluid only as last guy used after market. No issues since for me. No leaks. But never thought of these wires and corrosion there from the leak.

Actually I've never seen the grommets leak. What I do see very often. Is fluid overfilled and coming out the cap. It is the number one reason for premature brake booster motor failure.

Saw your post today and was like oh man I don’t think the shop would have cleaned off the brake fluid from the abs side black box wires at bottom or the two screws their terminals go into under the rubber cap! Out of sight location.

So I went now to check after having that leak two years ago, wish i had known sooner about cleaning this wire terminal area/ screws under the rubber cap. Will try to do more later with another type of brush. Started car and drove for 10 mins and all was good with performance and motor. Hopefully cleaning that area will help it last longer. Open to any other suggestions for better cleaning or how to keep maintaining.

But also have one brand new unit on shelf (bought in 2023) as this one that is going had grommet issue and it has per records new booster motor and accumulator put in in 2022. So i never used the brand new one. I also have that rebuilt guy's unit on shelf which was not correct one! Sent me 4 runner or GX one with smaller reservoir etc when I said please make sure it has the 99 LX one. I agree with you it’s very questionable what he’s doing. Anyway to each their own.

Best course of action, keep letting it go and whenever it does go out because of wire damage change to new full unit? Hopefully brake fluid didn't travel too far up the wires and just corrosion in that area only. Guess time will tell

Will do another bleeding soon as i'm about to do brand new Toyota calipers and brakes lines and shims and pads in few days myself. Will bleed via tech stream. Calipers and new things coming on because 1999 with 297,000 miles and I have good brakes (10mm) except for a squeal that comes from only driver side tire area (not booster area, checked many times) and comes only after many hours of driving. This began a 6 weeks ago after doing some hill driving for few weekends in a row. Now comes every few days after hours of driving and often in traffic. I am using engine braking.
Cleaned it, applied toyota proper grease with current setup, calipers seem harder than they should be to push in (do go in) but when testing some do not come out as easy as others. So with a sale figured i change everything. Rotors still look very good according to toyota and other mechanics. I will change this stuff out myself. Sorry for going off tangent but sort of related as i will be doing the tech stream bleeding. If rotors need to be changed after i change everything else in the area with toyota calipers, brake hoses, pads, shim kit etc, i will then redo the hubs and bearing job that did in December.


View attachment 3955458

View attachment 3955459

View attachment 3955460

You read this thread, SO HAVE UNDERSTAND OF HOW TO GRADE YOU MASTER.

The one thing to understand. These so called rebuilt master. Can't replace the seals, sealed within. Nor effective clean the ABS unit (black box). I do not recommend them.

 

[WanderingWarrior]

Cleaning, drying and packing wire boots with grease. Slow the corrosion, buying some time. But the resistance has already changed (increased) in wires. How much and for how long, and it's affected the motors commutator, IDK.

You can replace wire (brake control wire w/boots), screws and nuts. At same time inspec motors brushes and commutator.
Note: I've see Toyota parts retail counter. Charge as much as $350, just for the wire. It can be found for much less. I keep a few used and new in stock.

23-25 sec is like new. Indicates good motor getting very strong battery voltage, good accumulator and good heavy brake fluid void of air. Also indicates system holding pressure well (no leaks).


Actually I've never seen the grommets leak. What I do see very often. Is fluid overfilled and coming out the cap. It is the number one reason for premature brake booster motor failure.

You read this thread, SO HAVE UNDERSTAND OF HOW TO GRADE YOU MASTER.

The one thing to understand. These so called rebuilt master. Can't replace the seals, sealed within. Nor effective clean the ABS unit (black box). I do not recommend them.

Thank you so much for taking the time to write back!

How hard would it be to change and replace the brake control wires out without removing the unit from the car? I see two philips screws on each end of wires. So hard to see down there. But if one can do it with some tools from the top and side, maybe help of mirrors and borescope without messing up the tops of the screws that are corroded already. Maybe can do. Saw 2 videos of people removing the brake motor in parking lot. So maybe a ratchet with philips bit on it. And use some mirrors. But the motor end part of wire and screws will be hardest to do if i don't want to remove the motor.


I am pretty handy but if i have to remove a lot of the unit/ motor then I might as well wait to replace with the brand new full master assembly one I have on the shelf. As the brake booster motor is giving me 23-25 seconds during testing, not eager to change all of it yet. Love to do just the wires if possible.

So i found it from Impex Japan for $11.82 and 4screws and 4 nuts about $2 more and with shipping here to Canada will be about $30 usd total and no tariffs here for importing. Toyota dealers with $350 HA. That is a 3000% mark up
I order a lot of my toyota oem parts from impex or partsouq and saved thousands on brand new control arms and hub assemblies that were over 100% off of prices in North America. Calipers, brake pads and rotors weren't so I buy those here. Ordered all new brake hoses and all the hard brake lines ($3 each for majority and others like $8-12) that are still in production. Before they get discontinued. Got all except one discontinued. Will keep on the shelf. $3/ each for toyota. New Brake hoses to calipers I will change when putting on new Toyota calipers in coming days.

Wish i lived closer to you but am in Toronto, Canada. But i do visit California often, and if next time we do another road trip from Toronto, Canada, I will try to head to you!

 

[2001LC]

Removing motor, motor/pump or booster assy (motor/pump/accumulator) with master in place. You'll likely have issue with wire screws & nuts on ABS side. They'll very likely will need drilling out.

Pulling master is easy and fast. Only area some have issue with. Is install of hard line flare nuts. Tick is to clean and oil between pipe and flare nut, so flare spins very easily on the hard line/pipe. Then flare nut thread on by hand, 90% of the way. Only use your flare nut wrench and or socket, to torque down ~9 to 11ft-lbf. Then flush system.

It takes more time to R&R components, than the whole master assy w/booster.

Master were designed to last ~25 years. They can go longer. Depend on how much use and how well cared for. But in most cases, they not properly cared for. We then replace one part, and another fails. If you have a new master, on the shelf. It is a no brainer.

 

[WanderingWarrior]

Removing motor, motor/pump or booster assy (motor/pump/accumulator) with master in place. You'll likely have issue with wire screws & nuts on ABS side. They'll very likely will need drilling out.

Pulling master is easy and fast. Only area some have issue with. Is install of hard line flare nuts. Tick is to clean and oil between pipe and flare nut, so flare spins very easily on the hard line/pipe. Then flare nut thread on by hand, 90% of the way. Only use your flare nut wrench and or socket, to torque down ~9 to 11ft-lbf. Then flush system.

It takes more time to R&R components, than the whole master assy w/booster.

Master were designed to last ~25 years. They can go longer. Depend on how much use and how well cared for. But in most cases, they not properly cared for. We then replace one part, and another fails. If you have a new master, on the shelf. It is a no brainer.

I agree. I may just clean the wire screws more with cleaner on black box side (abs module i believe) and fill up with good dielectric grease and when it all does go out, i will put in the brand new master full assembly. Will try to also take a peak with the borescope on the far booster unit side wires to see if any corrosion/ brake fluid worked its way to that side of the wire connection.

For now things seem to be all working well with the 23-25 second booster cold start test time. Let's see how much longer i can get out of this unit. Interesting to see how long it will go.

Brake fluid (toyota) still clean, 2 years old and tested and less than 2% on test showing AND i will be doing lots of fluid change soon when putting on new calipers so that will be again good for the system. Reservoir also very clean. Perhaps it was all replaced prior to 2023 and me buying, i just see parts cost of $800 and line of brake master motor and accumulator and a military discount on the receipts like his other receipts with big lexus/ toyota discounts.

Grommet fix for past leak when bought 2023-
All i know is it was leaking heavily on transport truck, maybe it went up on an incline and someone had previously overfilled it, but leaking continued when i got vehicle in 2023 and grommet changed fixed it all. A pre-purchase picture also showed some leak prior to transport and they said it was engine dressing and not to worry. Had to be this as it was right under it. Makes me believe exactly what you say, people overfill these and don't know how to properly set the max line mark with proper testing first of getting fluid back into resevoir. So probably was overfilled for a while prior to purchase. Fortunately for me grommet change, with toyota 3 grommets fixed it all. Also at that time my brakes were doing great... just had a gradual leak happening and eating away frame paint on bottom.

Thanks again for all your help! So glad i at least saw this wire issue and went and checked yesterday and cleaned it and will do more. And will replace with new unit if current start giving issues. Won't replaced individual parts. Have a good day!