Poll on total brake failure in 100 series

[Beau]

This looks like the correct one from a 105 series. It uses a two hole fixing instead of the typical four and the connection point on the cylinder is different too, so more of the parts down the brakes line will be needed. But at that price, it's worth investigating and will definitely be the route I go when my brakes start acting up. If you get one of these to work, you'd never have to worry about them again.

4720160720 Genuine Toyota CYLINDER SUB-ASSY, BRAKE MASTER 47201-60720 | eBay

Condition:OEM 100% GENUINE NEW PART. East Asia and Middle East -.

www.ebay.com

 

[MountaineerLC]

View attachment 2378874

This looks like the correct one from a 105 series. It uses a two hole fixing instead of the typical four and the connection point on the cylinder is different too, so more of the parts down the brakes line will be needed. But at that price, it's worth investigating and will definitely be the route I go when my brakes start acting up. If you get one of these to work, you'd never have to worry about them again.

4720160720 Genuine Toyota CYLINDER SUB-ASSY, BRAKE MASTER 47201-60720 | eBay

Condition:OEM 100% GENUINE NEW PART. East Asia and Middle East -.

www.ebay.com

How much would the vacuum booster run? Unfortunately, I suspect the cost of retro fitting the brake system from an 105 or other LC would probably end up approaching the cost of the correct unit for the 100. (On a side note, were any of the 100's sold internationally available with a tradition vacuum booster instead of the electronic version?)

 

[uHu]

I recommend keeping the original booster in good shape, or just change it every 150 k miles. The car is homologated with the installed brake system, changing it could be viewed as unsafe.

 

[Beau]

Changing it could be unsafe, but look through this thread and you can see how many people have suffered. And this kind of failure seems to occur with not much prior notice thus in my opinion very unsafe. Plus this thread doesn't include the many failures outside of this forum.

Booster assembly looks like it runs around $500. I think overall you could adopt this setup for under $1000, but you'd be without ABS most likely and those with the traction control stuff would run into more issues with that.

 

[hoser]

There are at least (3) types of brake failures in this thread. 1) Accumulator/booster pump motor 2) M/C and 3) brake lines. M/C and brake line failures are common with all vehicles, so let's just put those aside.

I'm mostly interested in the folks who said, "the pedal went to the floor" "The problem was found to be a bad accumulator or booster motor."

The brake pedal is directly connected to the master cylinder piston and can perform braking function, albeit poorly, without a booster. I'd like to know where the fluid is going wrong if the M/C seals didn't fail and the pedal went to the floor. Does the bladder inside the accumulator fail, then absorb all the brake fluid from inside the MC?

 

[GTV]

Hey guys, please check my logic here. I need to make a $$$$ parts order ASAP.

Brake failure in a 2007 LC with 166k.
Driving at about 45mph on a smooth road the ABS, VSC, TRAC and BRAKE idiot lights went on and the buzzer under the dash sounded. Truck was driving perfectly.
Pulled over immediately to inspect, I could feel and hear the ABS MTR1 and 2 solenoids clicking.
Got back in the truck and drove maybe 5 miles or so until the brake pedal nearly hit the floor. Some braking was still possible if you really stood HARD on the brakes, it acted like there was no booster.
Brake pedal came back momentarily and was lost again.
Hooked up to a scan tool and got the following codes: C0278 (ABS solenoid), C1223 (ABS control fault), C1246 (MC pressure sensor), C1251 (pump motor locked/circuit open), C1252 (hydro booster pump motor), C1256 (accumulator pressure)

While diagnosing we were able to get the booster motor to occasionally kick on and provide temporary boost to the MC by tapping it with a hammer. The brake pedal would come back for a short period of time. So I'm thinking that the brake booster/accumulator is bad and the MC is ok? If the MC was bad I wouldn't get a hard pedal at all, correct?

Thank you for the advice!

 

[FxFormat]

Hey guys, please check my logic here. I need to make a $$$$ parts order ASAP.

Brake failure in a 2007 LC with 165k.
Driving at about 45mph on a smooth road the ABS, VSC, TRAC and BRAKE idiot lights went on and the buzzer under the dash sounded. Truck was driving perfectly.
Pulled over immediately to inspect, I could feel and hear the ABS MTR1 and 2 solenoids clicking.
Got back in the truck and drove maybe 5 miles or so until the brake pedal nearly hit the floor. Some braking was still possible if you really stood HARD on the brakes, it acted like there was no booster.
Brake pedal came back momentarily and was lost again.
Hooked up to a scan tool and got the following codes: C0278 (ABS solenoid), C1223 (ABS control fault), C1246 (MC pressure sensor), C1251 (pump motor locked/circuit open), C1252 (hydro booster pump motor), C1256 (accumulator pressure)

While diagnosing we were able to get the booster motor to occasionally kick on and provide temporary boost to the MC by tapping it with a hammer. The brake pedal would come back for a short period of time. So I'm thinking that the brake booster/accumulator is bad and the MC is ok? If the MC was bad I wouldn't get a hard pedal at all, correct?

Thank you for the advice!

Oh man AHC and now this? You just got this truck, did you even bring it home yet?


What you're describing sounds like the motor and booster is going bad, booster/accumulator holds the pressure built up by the motor, and that's what's supplying the power to the brakes. I had similar experience with my friend's LX, same thing you described and i changed booster/motor for him and it's been fine for over a year.

 

[GTV]

Oh man AHC and now this? You just got this truck, did you even bring it home yet?


What you're describing sounds like the motor and booster is going bad, booster/accumulator holds the pressure built up by the motor, and that's what's supplying the power to the brakes. I had similar experience with my friend's LX, same thing you described and i changed booster/motor for him and it's been fine for over a year.

Yep, just got it. On the recommendation of this forum I chose the newest, lowest mileage, best maintained vehicle I could afford. And I had to abandon it in Boise 500 miles from home!

Are there any other parts I’ll need to order or should the motor and accumulator do it?

 

[2001LC]

Sound like booster motor dead. If brake control wire corroded, it's very likely you've a dead spot on the commutator of the booster motor. Taps on the motor, will sometimes move armature just enough so brushes get off the dead spot and it fires up.

You can jump motor through the ABS unit. If that fails jump the brake control wire under it. If neither points fire up the motor, again points to commutator of motor. But watch out. Just as you hit motor and it started. It will sometimes start some times not..

You can buy the booster assembly, which is best. But probably only need the booster motor and brake control wire that attached to it. Also get the screws and nuts for the Brake control wire.

 

[GTV]

Sound like booster motor dead. If brake control wire corroded, it's very likely you've a dead spot on the commutator of the booster motor. Taps on the motor, will sometimes move armature just enough so brushes get off the dead spot and it fires up.

You can jump motor through the ABS unit. If that fails jump the brake control wire under it. If neither points fire up the motor, again points to commutator of motor. But watch out. Just as you hit motor and it started. It will sometimes start some times not..

You can buy the booster assembly, which is best. But probably only need the booster motor and brake control wire that attached to it. Also get the screws and nuts for the Brake control wire.
View attachment 2387157
View attachment 2387158

Thank you Paul.

 

[Poncherelli]

Is there a test for the accumulator? I have replaced the master cylinder with a donor one from an LX; and installed a newly refurbished motor; but 7 months later the motor failed. Doesn’t turn even connecting directly to power.

Is there a diag to find out why it died so quickly? I’m wondering if it ran too much because of a bad accumulator although I didn’t notice it running longer than the typical spec of a few seconds at a time.Just trying to avoid doing this repair for a 4th time!!!

 

[MUDZLLA]

Is there a test for the accumulator? I have replaced the master cylinder with a donor one from an LX; and installed a newly refurbished motor; but 7 months later the motor failed. Doesn’t turn even connecting directly to power.

Is there a diag to find out why it died so quickly? I’m wondering if it ran too much because of a bad accumulator although I didn’t notice it running longer than the typical spec of a few seconds at a time.Just trying to avoid doing this repair for a 4th time!!!

I had a bad accumulator and found the pump running almost continuously. A new pump saved the day for a while. I'd love to retrofit with an 80 series brake system, seems identical to the 105.

 

[azngarage]

i converted my to 80 series brake using booster, master and brake pedal assembly. The only hard part is modified the firewall to fit in the bolt pattern of the 80 booster.

 

[2001LC]

i converted my to 80 series brake using booster, master and brake pedal assembly. The only hard part is modified the firewall to fit in the bolt pattern of the 80 booster. View attachment 2414767

Interesting. Be cool too see write-up in a dedicated thread!

 

[spc7669]

i converted my to 80 series brake using booster, master and brake pedal assembly. The only hard part is modified the firewall to fit in the bolt pattern of the 80 booster. View attachment 2414767

Please do a write up on this. I’ve been wanting to start a separate thread on the feasibility of converting to a 105 type system. I had hoped some of the real experts on here could chime in on potential problems with the conversion.

 

[azngarage]

the conversion was done couple years ago. i'll try to take some photos and do a write up on it

 

[MountaineerLC]

i converted my to 80 series brake using booster, master and brake pedal assembly. The only hard part is modified the firewall to fit in the bolt pattern of the 80 booster. View attachment 2414767

Common bro, you just can't walk in here with a nonchalant post like that and not give more detail!

Seriously though, we'd love to have more details. Model year, cost, did you loose ABS, ATRAC, etc?

 

[2003LC100]

I might have a new variation to offer:

• Lost brake boost, ABS, brake, VSC lights went on and loud alarm tone went off. This happened immediately after slowly wading though a few inches of water. Condition went away for a few days, came back, went away after cutting off ignition and restarting car, then returned to stay. twice I got brake boost back for a few seconds with the alarm remaining on while driving.
• Didn't hear the pump running, haven't had any groaning sounds before this.
• Replaced the pump with a new unit from Ebay, still no boost and no sound from the pump.
• Tested the old pump with 12V, purrs very evenly
• Tested for 12V at pump terminals on both sides of the pump harness, as a relay clicks I can see 12V coming on for a second. This cycles on and on, but the pump is not starting.

Could the internals on the receiving end of the pump shaft under the accumulator be seized, preventing the pump from turning?

Thanks!

Edit: I was able to bleed the front brakes after R/R the MC to swap the pump, but at the rear I just get a trickle with a wide open bleeder after stepping onto the pedal with full weight dozens of times. Wondering if something major is wrong with the MC. MC was rebuilt with kit a few years ago. Truck still braked with major pressure applied but not very well.

2nd update: when bleeding at the MC I can bleed the 2 lines facing the front of the vehicle, the 2 lines facing the passenger side only weep, as does the line at the bottom (red line). This is done with system not pressurized as the pump isn't running.

 

[2001LC]

I might have a new variation to offer:

• Lost brake boost, ABS, brake, VSC lights went on and loud alarm tone went off. This happened immediately after slowly wading though a few inches of water. Condition went away for a few days, came back, went away after cutting off ignition and restarting car, then returned to stay. twice I got brake boost back for a few seconds with the alarm remaining on while driving.
• Didn't hear the pump running, haven't had any groaning sounds before this.
• Replaced the pump with a new unit from Ebay, still no boost and no sound from the pump.
• Tested the old pump with 12V, purrs very evenly
• Tested for 12V at pump terminals on both sides of the pump harness, as a relay clicks I can see 12V coming on for a second. This cycles on and on, but the pump is not starting.

Could the internals on the receiving end of the pump shaft under the accumulator be seized, preventing the pump from turning?

Thanks!

Edit: I was able to bleed the front brakes after R/R the MC to swap the pump, but at the rear I just get a trickle with a wide open bleeder after stepping onto the pedal with full weight dozens of times. Wondering if something major is wrong with the MC. MC was rebuilt with kit a few years ago. Truck still braked with major pressure applied but not very well.

Last first. Have IG key on while bleeding or flushing. At rear brake you need not pump pedal. Just have brake pedal pressed down with IG key on. Motor will run as pressure drops (bleeder opened). Don't not run motor more the a few minutes continuously at a time. Fronts, you do need to pump pedal. Never take foot off brake pedal, with a bleeder open. Or you will suck air into bleeder.

I'm unclear on where you're jumping 12v to the pump. We start test by jump at wire block on ABS unit. Then if that does not start motor, we jump at lead under ABS unit. If it then starts motor, you may have bad ABS unit (black box on side of master). Finally we jump at leads on the motor.

Here the tricky part. Sometime commutator on motor has a dead spot. The motor runs sometimes, sometimes it does not. It depends on where the motor brushes of stop or rather the commutator. If on dead spot or not. A clue that commutator is bad (has dead spot), is if, brake control wire is corroded. Very very often, we then find commutator worn out in that case. So what's so tricky. Motor fires up then doesn't randomly. So if doesn't fire up at first or second jump points, than does at third. Come back to first jump point and try again.

Do not reverse wire/jump. It will burn up motor.

 

[2003LC100]

Thank you 2001LC!

Last first. Have IG key on while bleeding or flushing. At rear brake you need not pump pedal. Just have brake pedal pressed down with IG key on. Motor will run as pressure drops (bleeder opened). Don't not run motor more the a few minutes continuously at a time. Fronts, you do need to pump pedal. Never take foot off brake pedal, with a bleeder open. Or you will suck air into bleeder.

The system was completely depressurized as I removed the MC to replace the pump motor with a new motor. After reinstalling the MC I bled the fan brakes with the ignition off. When I turned the ignition on the new pump did not come on. I tried to bleed the rears without pressure from the pump, which seems impossible, to brake fluid come out of the bleeders.

I'm unclear on where you're jumping 12v to the pump. We start test by jump at wire block on ABS unit. Then if that does not start motor, we jump at lead under ABS unit. If it then starts motor, you may have bad ABS unit (black box on side of master). Finally we jump at leads on the motor.

I bench tested the motor I removed and it started without issues. The terminal on the motor looked like new. The terminals on the ABS unit side are corroded. I used a volt meter to test both terminals. With the ignition on I get 12 volt on either, turning on and off as a relay clicks. I did not jump the leads as you describe.

Should I still do that test if I observed current at the terminals? Would this indicate the the new (not rebuilt) motor is bad?

Thanks!