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I would be, as this was the start of mine failing. I noticed that the motor was running a little longer at start up, and starting to come on more often. I didn't think too much of it as brakes seemed fine. We left on a 3k mi trip, at the half way mark it was coming on a lot so I flushed the brakes to see if that would help. It helped a little during heavier braking (downhill), but it was still coming on more than I liked. I ordered the parts to rebuild the master cylinder and replace the booster. Then one morning after our trip but before the parts came in the pump stayed on almost constantly, and when I pressed the pedal sometimes there was not enough pressure... so I parked it.I've read through all 48 pages of this post and it's gotten me nervous enough. I checked my car today.
2002 LX470 with 185K miles
The booster at start runs for 40 seconds but I noticed that there's 3 or 4x where it pauses for a quick second before continuing again. Connectors look perfect with absolutely no rust or corrosion.
Should I be concerned at all?
I just replaced the whole brake booster unit this morning. One of the easiest jobs for such a major component - 1.5 banana job. Helps that it's the whole unit.
If you're watching the video in post #900 not sure if it's the difference in models (mine's a 2006) but there's no need to remove any of the kickpanel/undershield pieces inside. You can get to everything without a problem (ABS unit, pedal pin, booster bolts). This model is also easier because you don't have to deal with the charcoal canister that is just forward of the booster, and all the related plugs and hoses.
Glad to have brakes again. But with 100deg weather and soaring gas prices, now she sits
View attachment 3034822
40 seconds is at the limit. The FSM recommends re-bleeding if over limit of 40 seconds.I've read through all 48 pages of this post and it's gotten me nervous enough. I checked my car today.
2002 LX470 with 185K miles
The booster at start runs for 40 seconds but I noticed that there's 3 or 4x where it pauses for a quick second before continuing again. Connectors look perfect with absolutely no rust or corrosion.
Should I be concerned at all?
If you checked/set fluid level after pump brake pedal 40 time with IG key off, and it was indeed low. And your seeing brake fluid around seal of ABS unit (black box on side of master) or the aluminium block between master and ABS unit. That was not spillage, or from being overfilled forcing out the cap. It is best to replace the whole Brake master with booster assembly. I've seen this a few times. There is seal plate between these. But Toyota will not sell to us, and leak may be internal.I had my brake light come on last night. Thought it was the emergency brake and then I checked the master level. It was low and looked to be wet on the lower part of the black box on the driver side. Brakes have been working fine but now I obviously have a issue on my hands.
Post booster doesn't say much about what you did and with what. A little to open ended.***Sorry, created a new post here so not to pollute this one with noise:***
Post Booster Replacement - ABS/VSC Lights with Codes
So after this replacement, now I'm trying to get my ABS/VSC lights to turn off. Warning sound and brake light have stopped. Booster assembly was done following the instructions posted by many. "Manual" flush then Techstream for all four corners to activate the ABS solenoids. After bleeidng with...forum.ih8mud.com
Happy Father's Day mud fam,
So after this replacement, now I'm trying to get my ABS/VSC lights to turn off. Warning sound and brake light have stopped.
Booster assembly was done following the instructions posted by many. "Manual" flush then Techstream for all four corners to activate the ABS solenoids. After bleeing with clear fluid and no air, LC brakes great. But I have the ABS and VSC lights that won't turn off nor will it clear them using Techstream.
I have the following:
C1223 - ABS Control System Malfunction
C1233 - Open/Short..Yaw Rate
C1244 - Open/Short...Decel Sensor
C1246 - Master Cylinder Pressure
I understand the C1223 is generic when anything in the ABS is not functioning downstream, so I'm guessing the C1246 is triggering this. Are there any troubleshooting procedures for any of these codes? Do they magically disappear after some driving? or have I done screwed something up?
The one thing I didn't do is drive on gravel as some have done to flex the ABS system but I figure that's what I was doing in TS for all four corners (4 seconds, resting, etc.) until all air and fluid ran clean.
Clearing DTCs in TS does nothing to these lights on the dash. They come on every time you start the car without pressing anything.
Any ideas?
I've not had to deal with these C1233 - Open/Short..Yaw Rate C1244 - Open/Short...Decel Sensor. But I'd start there. First making sure the Brake CPU (bolt on near pedal and in the way when pulling master) wire hosing block plugged firmly. Also check that all wire blocks fare ully plugged in master. Then set zero point.
Thank you,40 seconds is at the limit. The FSM recommends re-bleeding if over limit of 40 seconds.
Reason for long run time:
- Battery voltage low. Check voltage at cables first, and than on battery post. They should be the same. If not you've issue with battery terminals. Where something like oxidation is inhibiting current. If voltage the same, but low, say below 12V, we get a slightly longer run time. It's simple due to less power being delivered to booster motor. If voltage higher, say at 13V we get a shorter run time of brake booster motor. Due to motor turning faster. Corrosion on brake control wire, can also reduce current (increase resistance) to booster motor.
- Air in brake fluid system. Bleed and retest run time.
- Old brake fluid with high moisture contend. Result in less compressible fluid and lower boiling temperature of fluid. In this case, it simple takes longer to build pressure in fluid (compress fluid). Flush often!
- Leak. Leaks results in loss of pressure. This can cause brake booster motor to run excessively (longer than 40 seconds) and more often. Leaks can be external or internal.
- Bad flexible brake line. Damage of a flexible brake line at caliper, will flex or even get bubble/swells in the line. This too result in longer run times until pressure built.
If you checked/set fluid level after pump brake pedal 40 time with IG key off, and it was indeed low. And your seeing brake fluid around seal of ABS unit (black box on side of master) or the aluminium block between master and ABS unit. That was not spillage, or from being overfilled forcing out the cap. It is best to replace the whole Brake master with booster assembly. I've seen this a few times. There is seal plate between these. But Toyota will not sell to us, and leak may be internal.
Some have picked up used master and salvage the ABS unit and swapped in. But these is not recommended.
Post booster doesn't say much about what you did and with what. A little to open ended.
I've not had to deal with these C1233 - Open/Short..Yaw Rate C1244 - Open/Short...Decel Sensor. But I'd start there. First making sure the Brake CPU (bolt on near pedal and in the way when pulling master) wire hosing block plugged firmly. Also check that all wire blocks are fully plugged in master. Then set zero point.
I wenth through almost 1 gallon of Prestone DOT3 when I flushed my brakes a few months ago. I went through a few techstream abs bleeds on each caliper.
I just replaced my rear rotors/calipers (2007 LX) after having one seize up and make a mess while pulling out of my neighborhood. Next step is to bleed the brakes and I'm wondering is you guys use Toyota dot 3 fluid or something off the shelf. (I read here earlier @2001LC flushed 2 gallons while working on a problem rig. Thats a ton, especially at Mr Toyota prices.)
How much fluid should I have on hand to do a total flush? I bought two pints when I picked up the calipers but now that I'm thinking about it that doesn't seem nearly enough especially when I'm thinking about how much leaked out on the road. Thanks.
Thank you,
I did test the fluid level to 40 pumps and it's just below the max and is 35 seconds with key on for the motor pump. What is odd is that my fluid level seems to rise after sitting for a day or so compared to when I checked right after the light comes on. I am just going to replace the whole unit, Looks like I can pick one up for around 1300 bucks. Hopefully it last another 20+ years and I don't have to deal with it. Anyone have a part number for a 99 lx 470 complete unit with pump and accumulator? I seem to get mixed answers on what a "complete" unit is.
Thank you again
Thanks for that link, I ordered one up for 1220 shipped. Called my local to see if they would be close and they wanted 1750 and told him what I could find it for online to see if he would match but lowest he would go it 1575.Look around some Lexus dealers. I did search just for giggles and found some that would ship for free with not tax around $1200.
Lexus parts 17.76% off until July 5th
I went to my favorite Lexus parts website to price a few "LX" only items and saw this promotion. This is only for dealers participating in the "Simple Part" sponsored parts e-commerce sites, you can put your part # and zip code into Shop Lexus Parts and Accessories Online -...forum.ih8mud.com
Thanks for that info.The level will come up in reservoir as fluid pressure bleeds back off from accumulator. This starts as soon as pump turns off. It's why will see level change (go up) overnight or just hours after parked.
What most everyone and every shop misses, during a flush. Is flushing the accumulator! It's why I use more fluid in a flush than most. I use 3 bottle of Toyota brake fluid, about 1/2 bottle at a time, just to flush accumulator.
How?
Easy!
Once I've reservoir drained down (key on, brake pedal held down, open rear bleeder) to very near the bottom. Bleeder closed, key off, pump brake pedal 40 times. Level raises to about 2" from bottom of reservoir, as accumulator evacuates fluid into it by pumping brake pedal. I than add fresh brake fluid, to old in reservoir, doubling level to about 4". So I've a 50/50 mix of old and new in reservoir. Key ON, booster motor charges the accumulator again, drawing down the now with the 50/50 mix. Hold down brake pedal, IG key on, open rear bleeder and flush reservoir to very near the bottom again. Repeat 5 more times.
Than fill reservoir, and don't not let level below minimum as you bleed all four.
Running too much means the pump taking too long to pressure up (>20sec) or running too often (losing pressure in the system). If the pump is weak it can cause either one so replacing the pump may or may not help. If it doesn't the next easiest fix is the accumulator though most people rebuild the master. if you change the pump and rebuild the master and you get total brake failure it's the accumulator. But hey pump like hell because if the other two are good you can regain stopping power without fluid in the reservoir. Have fun!Not related to posts directly above, I'm thinking that it would be great if somebody knowledgeable would clarify what exactly "motor running too much" means in terms of how often, how long, when, where the noise is coming from, etc. Heck, it would be great if somebody would record the sound and post it here, so that anybody not expert on this has a good reference to work with. Like, "here is a normal sound" and "here is a warning sign". That would be very helpful, and may save somebody from trouble.
5Thanks for that info.
I ordered up a complete unit, how many bottles do you think I'll need for the install?