Fatal Design Flaw '01-'02 4Runner Brake Master Assembly $3k

[Mutant]

My 01 4runner has the ABS light, brake light and alarm going off - no brakes at the pedal and the ABS pump isn't coming on when you turn the key switch on. Other than buying a whole setup is there any other options that you or anyone else has found???

How many miles do you have?

Most of these Master Assemblies seem to fail around 230k miles.

You might get lucky doing a rebuild of your unit. However, you may not. There's not that much info out there for fixing these when they fail. In fact, Toyota recommends you do not even attempt it. Some guys have had luck tearing theirs apart and replacing cheap little parts like O-rings and springs. It all depends on how much time you can spend on it and how handy you are. I doubt you will find anyone who would rebuild it for you.

The most cost effective and easiest route is to buy a used assembly with 100k miles from eBay for about $490. Install yourself or get an import mechanic to swap the units for $200 or $300. Can get running again for around $750. And it should be good for at least 130k miles.

 

[Hepar]

I've heard of people swapping out their 01-02 MC with an older one.

 

[AuSeeker]

Just happened to see this ad and was reading this topic this morning and though if anyone is in this area...South Carolina....you might want to jump on this.

https://charleston.craigslist.org/pts/d/runner-hydrobooster-master/6352241884.html

 

[octanejunkie]

DAYUM, G

It's threads like this that make me glad I own a 99, and I will only ever buy a 99 or 00 4runner, unless just for parts.

 

[JayRolla]

DAYUM, G

It's threads like this that make me glad I own a 99, and I will only ever buy a 99 or 00 4runner, unless just for parts.

Don't be scared of technology and the future. You will miss out on a lot. Haha.

 

[octanejunkie]

Don't be scared of technology and the future. You will miss out on a lot. Haha.

My record player appreciates that sentiment [emoji3]

Sent from my Nexus 5X using Tapatalk

 

[anniesball72]

Master Cylinder Failing?

I think something is going on with mine now. In my case the pedal is firm but if I have my foot on it for a little in traffic, it does not return right away. Usually it's a 1 second delay or until the truck starts moving.

Did anyone determine if they can be serviced?

I've loved my 2001 4Runner since I bought it. Its been easy to work on and very reliable. Parts haven't been too expensive. I'm at about 230,000 miles and she still runs great.

HOWEVER...
The brake master cylinder assembly for the 01 and 02 is a bastard. Toyota changed the design to accommodate the traction control bs and made the unit very very expensive and treated it as a one piece assembly that should not be disassembled. Mine has started screeching a god awful metallic scraping death howl and throwing up all my dash lights along with dash alarm. I'm worried my brakes may fail at some point. I've spoken to 7 different mechanics in my town and no one wants to touch it because the design is unusually complicated and "different." They see the Nitrogen filled accumulator with Japanese writing all over it and their faces fill with panic every time. I finally went to the Toyota Stealership and they want over $3000 to replace the assembly. Their Master Mechanic came outside and told me I'm screwed and the assembly cannot be rebuilt (I don't really believe that yet). If I really had to pay that much this truck would become a total loss...that's more than it would cost to do a used motor swap..and maybe tranny too!

This master assembly part is impossible to find for under $1000 new. Its very hard to find used anywhere at all. After a full day studying and searching this I finally found one with 100k miles on it on Ebay for a decent price after some haggling. I have an independent import specialist mechanic installing it tomorrow. It shouldn't be that difficult of a swap but I'd rather let a pro do the brakes. I have my fingers crossed that the used unit will be good for another 100k or more. I got really lucky because this will probably end up costing only around $600 in total which is a lot better than Toyota wanted but still a lot of money. Especially when you consider that the failure could be caused by something as minor as a bad o-ring or spring under the accumulator. It may be the pump itself. Idk yet. If all goes to plan I'll be able to perform an autopsy on my bad unit and find the failure.

I'm posting this because it was rather difficult to troubleshoot and diagnose this issue on a 3rd Gen 4Runner. If I knew this could happen I may not have bought an 01. I probably would have looked for a 99 with regular brake master setup that is cheap to replace. There are very few info threads here on this topic that don't just dead end or OP pays the full $3k to fix. I actually found more info on IH8MUD. The 2000 Land Cruiser has the same master assembly setup and there are stories and videos of the same noise online. I feel like this issue should be covered in the 3rd Gen Buyer's Guide because although seemingly rare, it is a fatal failure for most budget rigs. Use this as a PSA/warning/whatever. If your 01 or 02 makes this noise, you may be quite ****ed.


video of the brake master assembly noise
https://www.youtube.com/watch?v=tlilHc0UyIk

 

[nevada]

I think something is going on with mine now. In my case the pedal is firm but if I have my foot on it for a little in traffic, it does not return right away. Usually it's a 1 second delay or until the truck starts moving.

Did anyone determine if they can be serviced?

it could be the connection at the pedal. might need a bit of lube. crawl under the dash with a flashlight, and take a look at the connection.

 

[G’s_4runnah]

Sorry to revive an old thread but has anyone thought about just replacing it with the diaphragm style from the 1995-2000 models? I’m thinking the bore should be the same size and the function would be the same. It would just be a matter of figuring out how to keep the abs running (and vsc trac) if you still want to run it. Anyone have any insight or know of any write ups?

 

[binqker]

Now I know why the master cylinders on the 01 and 02 are one of the first things pulled on these trucks at the Pick and Pulls.

Yep, and resell price goes up to $500 to $1000.!

 

[DerekRI]

Sorry to revive an old thread but has anyone thought about just replacing it with the diaphragm style from the 1995-2000 models? I’m thinking the bore should be the same size and the function would be the same. It would just be a matter of figuring out how to keep the abs running (and vsc trac) if you still want to run it. Anyone have any insight or know of any write ups?

Maybe combine the retro cylinder with the a version of the AndyMod to disable Trac / VSC? No idea, but as an 01 owner with a loud master cylinder, I'm interested haha.

 

[St Runner]

Also interested if anyone has swapped to an older version abs. I have no need for the traction control with a lsd in the rear. Have the older version laying around from my parts car, I imagine the hard part would be to keep the abs computer from freaking out

 

[pavelvoivoda]

Sorry to revive an old thread but has anyone thought about just replacing it with the diaphragm style from the 1995-2000 models? I’m thinking the bore should be the same size and the function would be the same. It would just be a matter of figuring out how to keep the abs running (and vsc trac) if you still want to run it. Anyone have any insight or know of any write ups?

You can downgrade to the more conventional simpler brake booster, and it is not too complex electrically. You just have to find all the parts, like booster, tubing and a load prop valve in the back. It's purely mechanical work, then you just directly connect the brake light on the dash to turn on in case the brake fluid is low, or if the e-brake has been pulled. Simple stuff.

What you can't do, is keep all the other systems - ABS, VSC, BA, EBD, and TRAC. The facelifted hydraulic brake booster and the control ECU above the brake pedal ARE those systems.

You can try to downgrade to the less sophisticated ABS only booster, but that's more complex wiring work.

Good news is that if you have the tools, and the FSM, you can correctly diagnose and repair your current booster. It's a bit of work, but it's doable. You have to do it by the book tho.

Most of the time it's the pump motor and pump assembly on the booster that makes the screeching noise and that part is on ebay for sale refurbished, but you still have to read the book to refill and bleed the system.

First share what the problem is with your brake booster, by reading the DTCs from the dash lights, and let us know and describe the symtoms, I will try to find some info and part numbers for the parts that you may need once you diagnose what the problem is.

Here is a diagram of the brake master I think you have. and a link to all the parts you can try to search for, after you find which parts are to be replaced or repaired.

http://toyotamarket.ru/us/671460/011/2/4702/1/47950D/

You can look up your catalog code in the link below if you want to be sure you are looking at parts for your 4Runner. The catalog code of your truck should be something like this RZN18xL-GKPxxx or VZN18xL-GKPxxx. Look for it on the driver's door sticker.

http://toyotamarket.ru/us/671460/

Pavel

 

[96RedRunner]

Tyler James Inc's Ultimate '01 SR5 - Toyota 4Runner Forum - Largest 4Runner Forum

Tyler's writeup on swapping to pre 01 MC post 30, 34 starts it, good read.

 

[G’s_4runnah]

Thank you guys this is exactly the information I needed!

 

[G’s_4runnah]

Tyler James Inc's Ultimate '01 SR5 - Toyota 4Runner Forum - Largest 4Runner Forum

Tyler's writeup on swapping to pre 01 MC post 30, 34 starts it, good read.

Is there any way you could link that? I searched through posts started by him and couldn’t find anything and then checked back through his build thread and only found a few posts seeping page 20. Sorry to be needy but I’ve always found this forum more difficult to navigate than tacomaworld where I started my forum browsing career.

 

[96RedRunner]

Pg 20 all there is with bit of text talking of using non abs master running new lines etc. A how to does not exist, it can be done.

 

[mbonifant]

I'm happy to help. This forum has helped me out a lot. Just want to return the favor.

I have another good condition Master Assembly for sale if anyone is interested. I bought a 2nd used unit as a backup because I needed my truck running ASAP. PM me if you would like to buy the other good assembly. 20lbs shipped from 79707. Paypal. $420 plus shipping. Good used unit. It is the entire assembly together.

I can also sell the bad Master Assembly if anyone wants particular parts off of it or wants to rebuild it. PM me.

Long shot, but any chance you still have the good condition master assembly? Mine’s starting to go.

 

[96RedRunner]

My 01 MC bit the dust @ 224k mi this past August 21 buy once cry once $23 Franklins

 

[jgue467]

That bites Big time.

My understanding (since mine hasn't bit it ...Yet) is they are rebuildable via a kit. See details in this post, its for an LC100 which is what our 01-02 systems are based on and use the same parts. Luck all.

Master Cylinder Rebuild - DIY | IH8MUD Forum