HenrySacto

Phil,

Thanks for the information. 47050-35010 is the same part number that dealer told me that they would replace. You are right, I would save $500 already to buy it from your site. For this part do I have to have dealer install it for me or a shop say Les Schwab or Brake Master can do it as well? At this point I will check to see if I could fix the problem by replacing just one of the components first...If not then I might have to purchase the whole assembly. I will difinitely let you know...

Thanks,
Henry

GSGALLANT

Anytime, Henry. Let me know if you need any sections from the service manual for the brake system, and I can email them to you. You could print it and give it to Les Schwab (if that's who you get to work on it), as I doubt they'd have any documentation on this system (I could be wrong.)

04 Rocko Taco

Turns out 9 toyota taco and 4R owners prefer Yotatech over the stealer for repair information. Funny eh? You can find a lot of great information and a wealth of tech knowledge and help from guys like GSGALLANT and folks like him, Yotatech....keeping the world a safe, happier place. Good luck. PLEASE don't pay $2500 for this.

MTL_4runner

Sorry, not sure how I missed this thread....

Here's a good troubleshooting table for your case:
http://www.deserted1.com/FSM/Repair_...r/trou/pst.pdf

Notice there is no mention of the ABS under low or spongy pedal so I would definately agree with GSGALLANT on the fact that more than likely your master cylinder is shot. You should still go through the procedure and check everything just to be sure you have eliminated all other possibilities, but that would be my guess as well (esp in a case where you claim to have no pressure at the brakes at all). Only other suspect would be a fairly major leak but you should also be seeing your brake fluid go down as well if that was the case.

GSGALLANT

MTL_4Runner: Although that troubleshooting table is for a vacuum assisted brake system, most of the problems can apply to the 2001 & 2002 hydraulic brake system as well. Good thought on the large leak as well.

Henry: I assume you've checked your brake fluid level and all is OK? I would contact the dealer and ask them exactly what they found when they told you your "Master Cylinder stopped functionning"... they might have actually done some troubleshooting and might know something that would help us help you save money.

littlerunner

ck out the parts & labot,your mast cyl has the abs,vsc unit built on,we just had to rpl one that someone drilled a hole in the unit putting in a stereo,the factory part lists for $2075.00,if you want i can sell it you for $1468.00,the labor sounds a little steep but way out of line

HenrySacto

Yes. Could you please email me the manual for the brake system just in cause I need it.

Thanks again for your great help!!

Henry

GSGALLANT

Sure... just let me know what your email address is (you can PM me if you don't want to post it). I didn't see anywhere that would let me attach files while emailing through Yotatech, so I'll have to email you outside of Yotatech.

MTL_4runner

Hehehe....yep, forgot you guys got switched over to hydraulic assist in 2001 (makes the troubleshooting a bit more complicated, but still doable). Then another place to look would also be the accumulator/pump since that might be absorbing the pedal force as it is applied. Post up the checklist for a "soft/spongy pedal" from your FSM if you can.....I'd be interested to see what it has on there for possibilities. Definately watch the brake fluid level as the brakes are applied.

GSGALLANT

Jamie: Good thought, but if there is no accumulator pressure, then when you press the brake pedal, the internals of the MC move such that the path from the accumulator to the rear brake loop is open (with no pressure in the rear brake loop) and the pressure applied to the brake pedal gets transmitted (with no power assist) to the front brake loop only. So although the pedal travel might be a bit longer in this condition at first, the pedal feel will be quite solid (compared to when you have power assist).

This can be demonstrated by pumping your brakes many times (read: 30 to 40) with the ignition in the "off" position. As you apply and release the brakes, the pressure in the accumulator will decrease, as the fluid is slowly moved from the accumulator to the reservoir (through the MC, of course) with each pump. Once the pressure is gone, your pedal will get solid as a rock when you apply the brakes, but the pressure is only going to your front brakes (many have scratched their heads while trying to bleed the rear brakes using the pedal method on 2001 & 2002 4Runners with the ignition "off", wondering why no fluid was coming out of the bleeders - after a while when the accumulator pressure is gone.) This, of course, is solved by leaving your ignition "on" while you're bleeding your rear brakes (truck does not need to be running, though.)

I've attached the brake troubleshooting list here so that you can get a quick look at it (not a lot of extra info, though)

Now, that being said...

Henry: Jamie's last post (absorbing pedal force) got me thinking about when you last bled your brakes... is there any chance that you let the fluid reservoir go really low as you were bleeding the brakes? Reason I ask is if you did, you might have let air get into your master cylinder, which may not come out easily when you subsequently try to bleed the brakes again. I'm not sure about our MC, but others often have to be removed from the vehicle to be bench bled if you get air in there... Just something to think about.

As another quick test, though, leave the ignition switch "off", then pump the brake pedal many times (40 or so) to see if it eventually builds up pressure. If not, then my vote is for one of the rubber seals on the master cylinder pistons (or MC cylinder bore damage - but not likely). The MC is rebuildable (read: you can take it apart), but I'm not sure about the availability of replacement parts. Ask the dealership (likely the only chance you've got to get parts) if they sell a MC rebuild kit (new pistons & seals).

GSGALLANT

Henry: I've just emailed you all the Brake Booster pages from the Service Manual. Good luck.

HenrySacto

Guys,

Here is the update:


I got another confirmation from a friend who owns a shop that it can’t be fixed and the whole assembly has to be replaced. So yesterday I decided to go shopping for a replacement unit at Auto dismantling shops. I spent a few hours browsing almost 10 shops and finally got lucky and found a unit. I paid $150 for it (MSRP for this brake assembly unit is around $1800). I took the part to my friend’s shop and had it the unit replaced. It only took him less than an hour to replace the unit and bled the brake. The total cost to have this problem fixed is around $400 compare to $2500 if I were to get it fixed at the dealer. The only different is that the dealer would put in a brand new brake assembly unit which I don’t really care. Anyway, the brake works great now…however, there is one problem and I’m not sure what it is…

Maybe you guys can help:

After stepping on the brake pedal for about 4-5 times and a few second later I hear this noise sounds similar to the car radio antenna when it goes up or down…the noise lasts about 3-4 seconds and it goes away…it does not come back again until I use/step on the brake for another 4-5 times. I suspect that the sound is being generated by the brake pump or something like that? I’ve never heard of this noise before when my original brake was working…any idea what it is or what I should do? I asked my friend and he does not seem to know what it is…should I take it to the dealer and have the brake diagnosed? The dealer might have the right tool or experience to tell me what is making the noise?

Please help!!

Thanks,
Henry

eric-the-red

From what I understand that noise is normal, it's the motor pumping up the accumulator pressure, you may also hear a click from the relay on the passenger side of the engine. Mine is barely noticeable but another 4Runner I was in was noisier, so maybe the loudness depends on the vehicle.

FingerMan20

those freaking abs modules are way expensive!!! $2500??? wow.

MTL_4runner

Wow, only $400 vs $2500 good job on the fix!
Ditto that is normal......maybe the previous version was just quieter and you never heard the pump.

HenrySacto

Jamie,

Are you serious that the noise is normal? It is really loud and unusual. I've been driving my 2001 4Runner for 4-5 yrs already and I've never heard this noise with the original brake system. Maybe this brake assembly unit that I just replaced is not working properly? I'm thinking about taking it to the dealer and have them check to see if there is anything wrong with it at all. Honestly, the noise is really loud and annoying...

Thanks,
Henry

eric-the-red

It's hard to tell without hearing it, I know on my 2001 my pump is very quiet. I can only hear it if I'm idling with the radio off. The only other 2001 I've been in it was more noticeable, but still not loud and annoying. Maybe it's a good idea to get it checked in case you damage the new one.

HenrySacto

Hi GSGALLANT,

I ran into your posting on another forum regarding the whirring sound after applying the brake for 5-6 times. I’ve been told by others on this forum that this sound is normal. However, I have never heard of this sound before for the last 3-4 yrs of driving my car when original brake was working. I’m not sure if the brake assembly unit that I just replaced is just making louder sound. Or maybe the whole unit is not functioning correctly. The sound is really loud and annoying. I’m thinking about taking the car back to the guy who replaced the assembly unit and see if he has any idea how to fix this. Or perhaps I should take it to the dealer and have them check the brake system?

Thanks for all your help!

Henry

MTL_4runner

It might be that there is still air in the lines causing the pump to be louder than normal (same as you'd hear on a steering pump when it gets starved of fluid). There should be some noise, yes, but not as loud as you are describing. Obviously we can't hear the sound for ourselves so we have to go by what you are describing. I thought it was just slightly louder than your previous setup, but it sounds like that is not the case.

GSGALLANT

Henry,

Like others here have said, the fact that the sound is there is normal. (Whirring is the pressurizing pump building pressure in the accumulator... clicking after the whirring is the relay clicking off.) What may not be normal is how loud the sound is.

To tell you the truth, when I first bought my 2002, I didn't notice the sound for the first few months. At one point, I was going over a bump while braking, and heard the clicking sound (relay) as soon as I went over the bump (coincidence). Being as anal as I am about abnormal noises in my vehicles, I spent hours in the garage wiggling the wheel, and moving the sway bar, and endlinks and other suspension parts around trying to duplicate the sound. I couldn't duplicate it (obviously), so I gave up. I started listening for it all the time, trying to diagnose it. That is when I first heard the pressurizing pump run. Now I hear it most times (if the radio is off)... not because it's any louder than it was, but just because I know about it, I guess.

In your case, it sounds like this pump/motor probably is just plain louder than the other one you had (or the other one wasn't working at all - Do your brakes now stop the car wayyyyy easier than they ever did... as in manual brakes vs power assisted brakes? I know that's not very likely, because you would have been questionning why it took you so long to stop before...)

Anyways, if you can hear it over the sound of the radio playing at a reasonable level, then something probably isn't right. If you can only hear it with the radio off and the windows rolled up, then I wouldn't worry about it.