Bad word!
What's a poor boy to do? If this fails can you run it long-term and just know you don't have ABS or does it disable or reduce your braking function? What preventive maintenance steps can be taken?
Thanks 96RR.

There are videos on YouTube of someone replacing just the electric motor that runs the compressor for the ABS master cylinder. From his video you can find the exact part number of the electric motor and its a little more then $400, and the job of swapping out the motor doesn't look too bad.

Twice now I have had that motor run backwards for a few seconds, causing a horrible screeching sound. When I stopped the truck the motor stopped turning the wrong direction and it hasn't happened for a while, but I know that is a sign of the motor getting ready to go out. That's when I started looking up how to replace it.

Definitely better to replace just the motor then the whole ABS Master Cylinder.

[edit]Looked it up... here is a link to the part that would need to be replaced:
2001 - 2002 Toyota 4runner *NEW* Abs Pump and Master Cylinder Repair Electric Motor - Wholesale Parts Express

@Zorrota , Start saving, Lol. Believe me I'm working on a plan.
There is one person on forum that has done a swap to pre 01.
Used is a option +- $600 range if lucky.
What happens when it fails depends on what part fails.
My info gets spotty on what happens when certain parts fail.
If brake pedal plunger seals of MC = no brakes, rebuild kit is $70.
The spotty part, Motor or Accumalator have brakes like in old days before power brakes no ABS. Maybe limp mode.
Motor/pump last I checked was $1100, Accumalator $350.

I've done all I can by flushing system a bunch with good Syn fluid when I first bought it.
When it rains I lock em up to function ABS.
Not trying to freak people out mentioning this, part of having a 01 02 there are cases of failures not a lot but it's there.

That's option hadn't seen. I have to wonder though if it's really the motor that's a problem. Parts diagrams don't show a check valve could be built into pump or accumalator bad/faulty check valve would cause motor to turn backwards.
Has to be a check valve in system for it to work.

So I am getting that horrible screeching sounds after start up. I hear it after morning and after work start ups when the vehicle has been sitting for hours.

YouTube

Anyone have any good news fixes they want to share?

No good news just news, folks on IH8mud said motor changed screech still there. I was thinking screech could be coming from motor rotor bushings being shot, sounds like bad thinking on my part. Wish I had one I could tear into. With above in mind maybe a internal seal/o ring leaking by under pressure makes a screech sound.

Right!?

All the half measure options are expensive, and then there is always a great chance that it doesn't address the issue.

I wonder how many people have tried to revert back to a pre 2001 system. I am sure it's not just that easy.

I thought I saw somewhere that sells them for about $1500. Not cheap, but better than the close to $3000 option from dealer / Camelback...

Mine makes the screeching some mornings but not others. Never happens in the afternoon when the truck is warm. From what I gather a brand new pump/accumulator seems to solve things. I think the posts I read on IH8mud that said their screeching didn't go away tried to have the motor rebuilt by an electric motor shop. But there was some comments about some shops not wanting to rebuild them because they were hard to do.

FWIW the motor/pump/accumulator is available new from some online Toyota parts dealers for $765. Part number 12 in that diagram/list.

Hydraulic System for 2002 Toyota 4Runner | Boch Toyota South

I think the fact that the 98-07 Land Cruiser have same part/issue as our 01-02 4runners is a bit lucky. Lots of those guys dealing with the same thing and trying stuff.

I'm trying not to get too worked up over it. If it is the pump/accumulator and $750 solves it, that's cheaper than a bumper or set of tires....

IIRC @Tyler JamesInc swapped when he put in a manual trans, needed room for clutch MC and got rid of the headache. Is something I've been thinking about not easy but doable. When time comes I'll be tearing mine open see what's up.

Before swapping to analog brakes...consider that the ABS system is, in effect, your diff locker. No ABS...You've got open differentials front and rear.


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Having open diffs would be the least of your worries doing the swap. ABS/VSC/Trac module inputs/outputs with ECM is where it gets complicated.
Then you have to do the hardware side of things if you want functioning ABS.
Best way to look at it is 2-4 months of car payments solves the problem for 200k mi I can live with that.

For those who have this issue, or will someday, I figured I'd paste a few links I've bookmarked researching things.

This thread is about rebuilding the master cylinder portion, which might be good to do if you have it out to replace the motor:
Master Cylinder Rebuild - DIY | IH8MUD Forum

This thread is about some people getting their pump motor rebuilt:
Source for rebuilt booster pump on master cylinder | IH8MUD Forum

Here's another thread on the noise:
Booster Pump / Accumulator Noise diagnosis | IH8MUD Forum

Finally, here are links from the FSM for diagnosing, removal, and replacement. Scroll down to the "Hydraulic Brake Booster..." section:
96-02 Toyota 4Runner Factory Service Repair Manual

Used units can be found on Ebay in the $400.00 range. Or, you can try your luck at a junkyard for less than $100.00. I figure if you're staring at $1500+, you might as well try a cheap route first.