Another tip, most here don’t use the search function on mud. Use google or your favorite search provider and do “ih8mud 200 series “ + your question. It’s a much better way to find threads related to the search.
Brakes ...... Overdue write-up.
- Thread starter 2001LC
- Start date
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Ok will add signature. Don't know why i thought this was 200 forum! I think i googled it and saw that it was related but i guess I'm mistaken. Thanks for your help!
Recently started having issues where I get brake dash lights and alarms for a few seconds. Very sporadic, sometimes while driving, sometimes while idle. I haven’t ever lost brake pressure, and braking has felt consistent the whole time. Pump takes about 35-36 seconds during testing and I don’t see any leaks. However, I bought the truck used and there was a bottle of valvoline “premium-dry brake fluid” in one of the drawers. Where do I start to try and fix the problem? Or do I need to go straight to replacing the whole thing? Thanks.
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Read through this thread from Post #1… will provide insight how to self diagnose your issue, and recommendations for prevention. Read through to glean as much info and background as you can.
You can look up any parts you may need on Partsouq… enter your VIN number for most accurate part numbers.
partsouq.com
Historically, right around Black Friday, Toyota online parts center usually offers 25% off plus free nationwide shipping. With the nature of the import tariffs that we are seeing in the United States right now, would probably be most cost-effective to purchase in country, rather than from overseas.
I don’t know how many miles on your vehicle, but if the brake master cylinder has been neglected, or it has been fed a diet of non-Toyota OEM brake fluid, your master cylinder may be in a state of decline, as described by 2001LC.
If you need help from the community, please provide the specific details of your situation. Because those will be the first questions that the community asks of you.
What year?
Current mileage?
Service history?
Rust and corrosion condition?
Current brake service status? Worn pads?
Any codes?
Any wiring anomalies? Bootlegged half assed wiring by PO?
Non-OEM components?
This information will help the community to aid you in diagnosing your issues over the Internet.
Read through this thread from Post #1… will provide insight how to self diagnose your issue, and recommendations for prevention. Read through to glean as much info and background as you can.
You can look up any parts you may need on Partsouq… enter your VIN number for most accurate part numbers.
PartSouq Auto Parts Around the World
We present to your attention our wide range of quality auto parts for many brands of cars. Our genuine parts catalogs and search by part number will help you!
Historically, right around Black Friday, Toyota online parts center usually offers 25% off plus free nationwide shipping. With the nature of the import tariffs that we are seeing in the United States right now, would probably be most cost-effective to purchase in country, rather than from overseas.
I don’t know how many miles on your vehicle, but if the brake master cylinder has been neglected, or it has been fed a diet of non-Toyota OEM brake fluid, your master cylinder may be in a state of decline, as described by 2001LC.
If you need help from the community, please provide the specific details of your situation. Because those will be the first questions that the community asks of you.
What year?
Current mileage?
Service history?
Rust and corrosion condition?
Current brake service status? Worn pads?
Any codes?
Any wiring anomalies? Bootlegged half assed wiring by PO?
Non-OEM components?
This information will help the community to aid you in diagnosing your issues over the Internet.
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- Thread starter
- #165
If you'd like to stop by , to have me to look over you 100 series. PM (DM) with your contact info.
_____________________________________
ABS alarm and its lights, come on. For the most part, are when pressure drops below a minimum threshold for a specific duration.
Brake light comes on. For the most part, are when E-brake on or when fluid low in reservoir.
You can test your pressure alarm is functioning, and learn what sound and lights happen when pressure drops:
- By simply, pumping brake pedal rapidly, with IG key ON (engine on or off). The more or less, rapid pumps, before alams. Is also a measure of health of system and fluid.
We can have alarms, on occasions. When brakes fluid is cool. Especially in mornings, when OAT lowest and brakes haven't yet been used. Cool brake fluid, meaning: Brakes not used for hours, so fluid not under high pressure. Keep in mind; pressure = heat The higher the pressure, the greater the heat generated. So, no thermal expansion when fluid cold. Rubber seals, in the system as well as all materials are contracted (shrunken) when cold. We'll get alarms for just a few moments. Then the more we use the brakes, generating heat. The more the brake fluid heats up, heating all components. Thermal expansion! The system now holds pressure, since all components expanded/tightened. So alarms & lights clear.
We may or may not see a leak in these systems. But for some reason, system is detecting low pressure. If we can't find the fault, and ABS alarms only when cold and not often. We can watch. If becomes more frequent, we must must take action. Which in most cases these days as fleet has aged. means a new brake booster w/master (the whole brake master).
Other times. Booster motor is running intermialy, when called to run by low pressure. This is very common, when commutator has a few bad spots. Tricky to diagnose. Since we get frick be it running when we check, by jumping with 12 volts.
Short or fault. Can also be inside ABS unit, which current passes through.
One example of not seeing a leak, yet system pressure dropping due to leak. Is when we hear squeal (dying seagull) and see bubbles in resevoir, without even pumping brake pedal. This is internal leakage past a seal in front of master. Often times we don't get a brake alam in these. The seal get worse with each failure to hold pressure. The sound is fluid passing the seals, under very high pressure. As it get worse, motor runs excessive long. Again we burn up motor.
We may also have situation of low voltage to brake booster motor. Thus system takes to long to build pressure.
Dealership, often replace the ABS CPU, as first step. I've yet to see a bad ABS CPU.
Many components in our braking system, must all working together as one. So we look for clues, as to possible problem areas.
_____________________________________________________
I had one with only 24K miles on it. It had intermittent brake alarm. It was diagnostic as just needing used more. I found a number of issues, i had to work through: low-mile-case-study-24k-07lc
___________________________
In another with alarms:
That had alarms for no apparent reason. I had to replace a brake master and found while doing the R&R.
Where ABS alarms and lights where coming on. This would happen occasionally. For the most part, during cold start up (first drive of the day). In just a matter of days, became more frequent.
It's reservoir was only mildly stained, in this 06LX w/230K miles.
Fluid flush with Toyota brake fluid, few years earlier. Unknown what fluid(s) used before then.
About 30 pump, until evacuation. Not bad for age.
Time to pressurize system, for full evacuation (40 pumps IG key off) with 12.5V. about 33 sec IIRC. Not bad for age.
Fluid a little bit on low side, but above low line. Rear brake pads low, wear indicator sounding off. Fluid does drop as pads wear.
Brake caliper and flexible brake lines inspected for leaks. Non found.
The leads/wire at bottom of ABS unit, had been look at few years ago. Which were okay (no corrosion).
2020 pictures of ABS leads.
So this brake system, other than pressure alarms. Graded fairly well in 2020, and now. But I'll admit, I did recheck brake wires under boot. Since I knew hadn't had spillage or resevoir overfilled since I inspected in 2020.
Still I was 98% sure, issue was in the masters. Most likely internal leak or fault in ABS unit.
While replacing the brake master. I found the leak. It was, at the ABS unit.
Wet ABS, in 2025
Wet ABS side of wires, in 2025
wet motor side wire, in 2025.
New master problem solved.
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Sorry it’s taken me so long to reply. I’ve moved to WA so the time for an in-person inspection has passed, but I appreciate the gesture. Let me add some details: 2003LC, 223k miles, non-Toyota brake fluid was likely used in the system since I found a bottle of it buried in the rear drawers. After the alarms turn off, I usually hear 2-3 pump sounds at one second intervals. I can’t figure out how to add a video. I will say I haven’t had the alarms come on in a few weeks…
System evacuates at around the 25 pump mark, takes around 36 seconds to recharge. No leaks found in lines. No corrosion or fluid on the ABS leads themselves, but it’s grimy down there for sure. Might be due for a surface clean and OEM fluid flush/refill just to see if the issue ever comes back. I have not lost brake pressure at any point and the ABS still does what it’s supposed to.
Post video in YouTube, then link here.
This may, be a sign of a brake fluid leak
View attachment 4036177
I agree that this looks like brake fluid weeping out of the ABS module…
As a secondary sign of confirmation, what do the other bolts look like that hold the ABS module together? Brake fluid would cause crusty surface corrosion as appears to have happened to this bolt. If all of the other ABS module cover bolts look to be in better shape than this bolt, I think that brake fluid leak is confirmed.
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- Thread starter
- #169
All clues need consideration. Even dust that has collected/stuck in/to area and not others.
Get phots from below and fender well below. Rinse, spray with degreaser and wash & dry. Get phots showing perfectly clean and dry. Watch! We usually find some wetness, starting near bottom, if ABS leak.
Make sure no wetness 360 degrees around reservoir. Some say, reservoir grommet leak. But, that I've never seen. What I do see very often. Is leak from cap, when overfilled.
Inside boot will normal get wet, but not always. Depends on how bad leak, for how long and where. These ABS unit leaks, usual get worse. They are a pressure loss. Resulting in pressure alarms. They'll eventually result in excessive long booster motor run times. Motor will then fail prematurely. Motor fail to run, no brake fluid pressure, little to no brakes.
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I would agree, that master will need to be replaced in time. Mine started like that but quickly I noticed the whole master slightly damp on that side.
Video of the sound I was referencing ^
Front and underside where the ABS module meets. I wiped it off about a month ago, haven’t touched it since.
They all look to be similarly corroded, although that may be another wet spot starting at the bottom left
- Thread starter
- #172
Open hood, and Video the brake reservoir, during sound event. Like seen in first video of OP of this thread.
I do not see leak in picture of brake master, you posted.
I do not see leak in picture of brake master, you posted.
2001lc,
I have a March build 2000 lc with 265,000 odo. I’ve owned it for 16 years and never flushed brake system and never had an issue with it.
Got the constant beep and dash lights a few days ago and immediately drove home and found this thread. Following direction given to others, I opened hood, turned key to on position without starting. Observed that my abs pump isnt pumping at all. The only audible sound i can detect is one or 2 of the abs solenoids clicking every 10 seconds or so.
Does this sound familiar? Thanks man. /Clay in Arkansas.
I have a March build 2000 lc with 265,000 odo. I’ve owned it for 16 years and never flushed brake system and never had an issue with it.
Got the constant beep and dash lights a few days ago and immediately drove home and found this thread. Following direction given to others, I opened hood, turned key to on position without starting. Observed that my abs pump isnt pumping at all. The only audible sound i can detect is one or 2 of the abs solenoids clicking every 10 seconds or so.
Does this sound familiar? Thanks man. /Clay in Arkansas.
Well I hoped for some wisdom from the subject matter expert but it can’t wait til xmas. I’ll keep studying!
After reading this helpful thread, i intend to purchase a “brake booster assembly, with master cylinder”. Oem part #47050-60012.
$1432 on toyopartsdeal
Several times within this thread its mentioned that users replaced one brake component only to have another fail shortly after. I want to avoid that if possible.
Can someone confirm that this part number (above) includes all of the major components. That would be super helpful as I am unable to tell by looking at it.
$1432 on toyopartsdeal
Several times within this thread its mentioned that users replaced one brake component only to have another fail shortly after. I want to avoid that if possible.
Can someone confirm that this part number (above) includes all of the major components. That would be super helpful as I am unable to tell by looking at it.
I recommend that you go to Partsouq…
Input your VIN # and lookup the part for your specific vehicle to confirm the correct part #. Once you determine the correct Part #, I believe that you’re on exactly the right path by replacing the entire brake booster assembly with master cylinder… considering your issues, and the age of the vehicle.
And, I recommend that, going forward, you try to adhere to the OEM suggested brake fluid replacement schedule, not to exceed every 3 years for brake fluid flush.
Only use genuine Toyota DOT3 brake fluid from a fresh, unopened container in these vintage vehicles. The genuine Toyota fluid is reported to contain a proprietary copolymer that is utilized as a seal lubricant. This will inhibit rubber seal degradation within the brake system.
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Well put Unruly and thanks.
I do exactly like above but I also take that PN to a Toyo site and check it to see if it’s been updated. Clean fluid is your best shot at long life parts.
Updating thread on my situation:
Has not happened again, finished long drive back to California from Washington and back, no issues. The noise I sent in the video happens post-alarm, which only ever happens when driving, so I’ll try and get a video of it but the likelyhood is very slim as it only happens for a few seconds
Has not happened again, finished long drive back to California from Washington and back, no issues. The noise I sent in the video happens post-alarm, which only ever happens when driving, so I’ll try and get a video of it but the likelyhood is very slim as it only happens for a few seconds
First off, thanks and kudos to @2001LC for all the diagnosis and detailed consideration that makes this and other threads solid gold. Respect.
I have an observation and a question...
I was wondering why an aged accumulator takes MORE brake pedal presses to discharge, compared to a newer one. This seemed counterintuitive, in that a newer unit might be expected to hold its pressure better and therefore discharge more pedal presses before it is empty. I'd like to test the following possible explanation for this, as I am certain that 2001LCs observations of this behavior are correct.
In the accumulator, the booster pump pressurizes brake fluid against the nitrogen filled chamber, separated by a diaphragm. If that chamber has become depleted of nitrogen over time because of gradual leakage, then the pump might have to pump a larger volume of brake fluid into the chamber before it reaches the switch-off pressure. Does this explain why you get more brake pedal presses out of an aged accumulator compared to a new one?
*If* this is correct, then there are a couple of implications. One is that the pump refill time of 30-40 seconds is mediated partly by booster pump performance and partly by accumulator aging. The second is that we could conceivably have a booster pump that is still perfectly good combined with a working but aging accumulator. This would give close to normal braking performance, but booster pump run times that are starting to rise, as well as an accumulator that starts to take more pedal presses to empty. (And of course we could have a failing booster pump as many have found.)
In my case I am getting 48 pedal presses to discharge the accumulator, and a booster pump refill time of 34 sec. So within spec, but more pedal presses to empty than expected. (# of pedal presses must also depend on how hard each pedal press is - I was not pushing very hard each time.)
So no concerns about the brake performance - all in spec - but I am wondering if a new accumulator would a) reduce booster fill times and b) the number of presses to discharge the accumulator. If all the above is correct, it ought to.
This is more a theoretical question than a practical one, as the wise but $$$ course of action is to replace the whole dang thing when it starts to fail.
Thoughts?
(Supplementary info: Owned car 18 of 24 years, 350,000 kms, in my time always Toyota fluid flushed regularly & correctly filled to max level with accumulator discharged. Booster pump wire terminals spotlessly clean, zero corrosion. No alarms or braking issues. No master cylinder seagull noises. Brake reservoir is clean. New genuine T calipers F&R inc. bleed nipple covers. No evidence of any hydraulic fluid leak anywhere in the system.)
I have an observation and a question...
I was wondering why an aged accumulator takes MORE brake pedal presses to discharge, compared to a newer one. This seemed counterintuitive, in that a newer unit might be expected to hold its pressure better and therefore discharge more pedal presses before it is empty. I'd like to test the following possible explanation for this, as I am certain that 2001LCs observations of this behavior are correct.
In the accumulator, the booster pump pressurizes brake fluid against the nitrogen filled chamber, separated by a diaphragm. If that chamber has become depleted of nitrogen over time because of gradual leakage, then the pump might have to pump a larger volume of brake fluid into the chamber before it reaches the switch-off pressure. Does this explain why you get more brake pedal presses out of an aged accumulator compared to a new one?
*If* this is correct, then there are a couple of implications. One is that the pump refill time of 30-40 seconds is mediated partly by booster pump performance and partly by accumulator aging. The second is that we could conceivably have a booster pump that is still perfectly good combined with a working but aging accumulator. This would give close to normal braking performance, but booster pump run times that are starting to rise, as well as an accumulator that starts to take more pedal presses to empty. (And of course we could have a failing booster pump as many have found.)
In my case I am getting 48 pedal presses to discharge the accumulator, and a booster pump refill time of 34 sec. So within spec, but more pedal presses to empty than expected. (# of pedal presses must also depend on how hard each pedal press is - I was not pushing very hard each time.)
So no concerns about the brake performance - all in spec - but I am wondering if a new accumulator would a) reduce booster fill times and b) the number of presses to discharge the accumulator. If all the above is correct, it ought to.
This is more a theoretical question than a practical one, as the wise but $$$ course of action is to replace the whole dang thing when it starts to fail.
Thoughts?
(Supplementary info: Owned car 18 of 24 years, 350,000 kms, in my time always Toyota fluid flushed regularly & correctly filled to max level with accumulator discharged. Booster pump wire terminals spotlessly clean, zero corrosion. No alarms or braking issues. No master cylinder seagull noises. Brake reservoir is clean. New genuine T calipers F&R inc. bleed nipple covers. No evidence of any hydraulic fluid leak anywhere in the system.)