YUP, ITS POSSIBLE TO DRIve it around in that state, depends on your badt assery level.lol/
drove mine like that for over 2months, while waiting for a replacement booster assy, the brakes still work, just needs gretaer foot pressure to engage the brakes, and greater braking distance, you will most likely rear end someone in a sudden stop scenario
........ not everyone is cut out for such, its not very safe either.....

Yes as stated it is possible to drive it but I would highly advise against doing so, you would be risking an accident and if it just a one vehicle accident then you took that risk, BUT you would be putting at risk every driver on the road anywhere near you and that's just not right!!

That being said if you do choose to drive it be prepared to also use the parking brake, if it works and also downshifting if at all necessary, you would be very surprised would well you can stop if you slow down ahead of time and then downshift through the gears at the proper time/RPMs/speed and then use the parking brake along with what brake you have after you get it down to 5 or 10 MPH, just keep in mind that you will need to do a little practicing using the parking brake in a safe place such as a parking lot without many cars around to be able to release it when needing to proceed forward, I had to do this to get my T4R home late at night 3 years ago on Thanksgiving evening, the only reason I took that risk was because it was late at night and very, very few vehicles were on the road, I had no brakes at all other than the parking brake because I had a brake line break and lost all the brake fluid, I would have repaired it before driving it home but being a holiday and also very late there were no auto parts stores opened.

Now as far as the dealership confirming exactly which part of the master cylinder is at fault, I wouldn't count on that happening, they really have no way to test each part of the assembly to determine which part is at fault and most likely wouldn't do it even if they did, the policy at most if not all dealerships and not just Toyota is to replace the entire unit to cover all the bases and get it fix without having to risk a liability.

05 06 07 08 09 Toyota 4Runner ABS Master Cylinder Brake Pump Booster A – Car Parts Direct

Can anyone confirm if this is will work?
Seems like a pretty good deal for the whole assmbly and it says it has a 1 year warranty + free ship...
For some reason, it notes for an 05-09, but weren't the 03-05 the same?
Any feedback would be appreciated!

Does not work, you need an 03-04. The ABS?VSC system is different on the 05+

If that is the complete assembly then it is a very good price, but because how they discribe it I'm thinking is might just be the pump assembly, i.e. the electric motor, pump and actuator, if that's so then it about the right price foe what you can get an OEM pump assembly on ebay, they do have a toll free phone number so I would call them to verify what it actually is.

That all being said I really don't think it will fit you 2003, I think that the assemblies changed in mid to late 2005, so I don't think it would fit a early 2005 but most likely will fit a late 2005, if you noticed they have a note....

"CHECK DATE 2005 MODEL- 4 RUNNER 2005 Actuator/Pump Assm; From 10/04"

Meaning it will only work on 2005s with a build date after 10/04, usually they start building the next year's models around mid year before the actual model year date, so there were many 2005 models build in 2004 and then into 2005 to around the middile of that year.

As an example of how some parts can change/be different on the same year model I know my 2004 V8 was built in 08/03 and has a 2003 era belt tensioner pulley on it (4" or 102mm) but later 2004 V8s have a smaller pulley on the tensioner (3 1/2" or 90mm), I had to get the pulley for a 2003 because all the part stores I went to (5) only had the 90mm pulley listed for 2004 model V8s, this also affects which serpentine belt size it takes as well, I had a hell of a time removing the old belt because whoever replaced the belt just before I bought it had the belt listed for a 2004 on it but that belt fits with the 90mm pulley, I don't know how they even got it on there because the tensioner was maxed out as far as it would go and I couldn't get the belt to get loosed enough to remove it, I instead removed the pully bolt and then pried the old pulley off which was the only way short of just cutting the belt to get it off.

Hi Danny, i was having the same issues, same model year and approximate mileage. What happened is that the motor controlling your hydraulic brake pump is wearing out. (much like how an rc motor will die out over time) I was able to purchase a refurb part and replace this piece without detaching my brake lines. it took about 20 minutes and saved me a big chunk of cash.. let me know if you have other questions


2003 2004 2005 TOYOTA 4RUNNER LEXUS GX470 ABS Brake booster Pump motor (REMAN) | eBay

This will not work. your ABS and Brake Assembly are different.

Why do you say his is different?

From what I see in the eBay listing it should fit his 2003 T4R.

Hey JURONIN, thanks very much for the info! Any chance you have a write up that replace?
Also, going back to 4RunnerMexico's post, was that how you determined that the motor, not the accumulator, was bad?
Would it be prudent to replace both, or unnecessary?
It sounds like I could replace the motor myself but the accumulator would likely need to be done by a mechanic, yes, no?

Tomorrow a.m., I pick up (likely getting a tow for safety reasons) my 4r from Toyota service center (they still think I may trade in for a new car).
At this point, I just need to decide if I bring it to the mechanic ($340 quote for the install) or home... as I don't want to rack up unnecessary towing fees $$.

Anyone able to help with my last couple of questions ^ ?
Would be much appreciated!

to shed more light.
a leaking accumulator will make the motor run too frequently...and eventually burn out, leading to complete brake failure.

yes, the method outlined by op above would tell you if the motor is still good or toast.
turn on the ignition, open the bonnet, depress the brake pedal, if you hear a whirring sound , then thats the motor actuating/pumping to fill up the reservoir, so you can determine right away, that you need to change just the accumulator $190 verus buying a used complete brake-master cylinder assy from ebay for $500 or more.

am still waiting for the step by step process or video of replacing the accumulator, as my motor runs ok, just that i have determined that i have a leaky accumulator, and need to change it out.

finally, the motor may overwork and burn out, taking out the 40amps abs/brake fuse , thus when you replace the complete brake mc assy, it would not work.
so do remember to check that fuse if your motor fails to actuate

Holy fug that is expensive OP.

Is this a common problem?

So I did the test and the MOTOR was definitely NOT running.
I ordered a replacement from eBay. It arrived Tuesday.
I just took a look to see about replacing the motor WITHOUT removing the whole assembly, disconnecting the brake lines etc., like JURONIN mentioned.
I don't see how you could possibly reach both screws holding the motor with it still attached to the vehicle??

Anyway, this video shows exactly what needs to be done (thanks JURONIN!):

YouTube

Seems pretty straight forward, just remove the unit, replace the motor, re-install. I'll just need to bleed the brakes once it's re-installed.

Great! I can knock it out this Saturday.

..... BUT I noticed signs of a leak, please see pics.
The leak appears to be on the OPPOSITE SIDE of the accumulator, around the bottom of the black box.
So, now I am stuck again because I don't know what is leaking/what other part(s) I need.

Any ideas?

(Also thanks for the heads up on the fuse! Will keep that in mind).

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Yes, apparently it is quite common.

Thanks for the youtube link,
if your motor is toast, it was likely caused by a leaking accumulator, so changing just the motor alone, would be postponing the evil day, i think buying a complete used unit will be a better option, and keep your failed unit for spares/back up.

btw, did you check the 40amp fuse, that powers the motor to be sure its not shorted out??