Vx or grande brakes/abs/traction control unit

[jjgsxr1000 Junior Member Find all posts View Profile Close jjgsxr1000]

Hi all.Well after replacing the dead Brake mastercylinder/ABS module in my sisters 2001 VX 12 months ago, it has died again. As people with a VX or Grande would know, they dont use a conventional brake booster & master cylinder..... This one makes a loud Humming noise from one of the pumps or accumulators on the unit on start ups & also intermittently when driving. My question is, has anyone found anyone at all that can replace parts on these units or service them at all? It appears that it is the same pump/accumulator that must die on all of them & a new unit is over $3000.00 Have found them 2nd hand (hard to get) for approx $500-$700 but dont want to keep throwing used parts at it all the time. I am a Mechanic myself & have contacted my Brake guys with no luck............ Any help would be greatly appreciated Regards, Jay

[where2next Lurker Find all posts View Profile Close where2next]

G'day all. Finally I've had enough of trying to sort this problem myself and am seeking the assistance of other poor unfortunates with Brake booster problems. Maybe between us we can come up with a solution.
Over the past year I have bled the brake system myself and had a brake specialist fully bleed them. I've had the Accumulator changed and the Brake booster motor but still no fix. The sound does go away for a while after each attempt but after a few thou k's it comes back exactly the same.
Video is at http://www.youtube.com/watch?v=sh14T2Yq2ZE as Prado brake booster sound.
Jay, I talked with my mechanic and he did mention a guy in Brisbane who reconditions accumulators and motors but I shy'd away from that because I reckon the cars important stopping type parts should be working at the top of their game. I dont know if recon parts can do this. As a mechanic what do you think?
From the vibration after the booster motor stops and that I've changed the accumulator and motor, I guess the problem is in the body of the assy. Can anyone explain whats in the guts of a Prado ABS brake booster? Cheers, Brett

[jjgsxr1000 Junior Member Find all posts View Profile Close jjgsxr1000]

I just had a look at the You Tube clip.
Exact same noise.
My Sisters one makes the High Pitched noise for a lot longer though.
Do you know the name of the guy who reco's the Accumulators?
I still have the last unit here i replaced, it might be worth a shot to mail him one.

Regards, Jay.

[jjgsxr1000 Junior Member Find all posts View Profile Close jjgsxr1000]

P.s, i might dissassemble the old unit i have to have a looksie inside it after i find out if it can be saved or not.

Regards, Jay.

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

On the vid, it sounds like it is a relay clicking away, I take it you have the traction control option.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Never had any issues with myn but it did make the same noise as yours BUT that last bit where it makes a funny noise just before it stops myn didnt do that. It would pump then just stop without that shake or quirky sound........Cheers Steve

[jjgsxr1000 Junior Member Find all posts View Profile Close jjgsxr1000]

On the vid, it sounds like it is a relay clicking away, I take it you have the traction control option.

Yeah Crooza, its the cars with VSC and Traction control that have this setup.
My car has been fine but my sisters has died twice now.

The noise sounds like a pump that is trying to prime up.
Like it is running dry.
Sounds horrid, then when it gets really bad it can set off an alarm while driving to warn of Brake Failure.

Regards, Jay

[Leethal Advanced Member Find all posts View Profile Close Leethal]

Hi Jay,

I was researching something else recently and came across a reference to a specialized bleed requirement for the accumulater/pump assembly. How have you been bleeding the system, perhaps there is a air lock present in the pump assembly or its drive mechanism which causes accelerated wear or similar?

Just a thought.

Lee

[spamwell Member Find all posts View Profile Close spamwell]

just to clarify, on abs cars the brake light comes on to tell you the abs is disabled, and the car will operate on normal brakes.

ive heard mine do the noise a few times over the last two and bit years but it seemed to go away, ive changed brake fluid since and have not had any probs, hopefully it stays that way mine is a 97 grande

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

No spamwell, the ABS light will illuminate to say there is an issue with the ABS. If there is a brakes issue seperate from the ABS then the brake light will illuminate instead, this as far as Im aware from memory is the same light that is illuminated when hand brake is on.........Actually Im sure all this would be well explained in the manual if you have it.. I never did read it in regards to warning lights...Regards Steve

[Kowolski Member Find all posts View Profile Close Kowolski]

Isn't that just the pump that keeps the vacuum correct on the power assist? if so, repeated cycling would imply a leak I would have thought. I have another car (German) and they came out with a mod after it was released that added a pump like that. The reason was the vacuum booster use to bleed down when the car was off for extended periods and when you started it there would be a short period where there was no brake boost for several seconds on start until the engine had run long enough. The manufacturer found owners were a little unnerved at pedal force required in those few seconds aft start on a hill. Solution was one of those pumps which brings the vacuum to correct levels as soon as the ignitions turned on. I believe pollution control came into play for some reason too.

If the Prado boost is anything like that I'd reckon there might be a vac leak somewhere.

Don't know anything about prado brakes at all so could be completely off the mark but it's just my 2 cents worth.

[where2next Lurker Find all posts View Profile Close where2next]

Had some intimate time with the beast today following advice that it sounds like air stuck in the brake actuator tubing on the front of assembly. Checked as much of the brake lines as possible but couldn't find any tells of a leak.
Jay, my booster motor doesn’t run very often, really only when i use the brakes and only after 10 minutes of idle. Also has never caused the ABS fail light to validate its existence. When i pump the brake during idle the warning lights come on for an average of 3 seconds.
After a bit of research I'm thinking that Leethal has hit upon something. I've seen several references to special tools or procedures for changing brake fluid in VX Grande Prados. Maybe the callipers do need to be isolated during the procedure as a drop in the line pressure during bleeding causes air to be sucked back past calliper piston o-rings into the tubing (Venturi effect?). Slowly this air makes its way back up the brake tubing causing several reports of spongy brakes we've seen around here. In GX GXL's, eventually the air bubble gets to the master cylinder and reservoir but in VX's and Grande's it can get stuck in the ABX actuator tubing. What you all think?
I just bleed the brakes like always by opening and closing the nipples while pumping the brakes to pump the new fluid thru. First time I did it I sort of forgot to notice exactly when the sound went away but it was gone when I gave it a test run.
Jay, I also found an interesting schematic diagram for the system on the net which might help with your rebuild of the old unit but I'm not sure if I can post the link to it here. It was something like toyo(D)o (I)t (Y)ourself.com.
Now I'm thinking of taking it to the dealer service shop for a brake fluid change $$$.
By the way, I also cleaned the air conditioner filter behind the glovebox. Looked like a sheet of 60 grit sandpaper with some leaves and feathers stuck to it. A highly recommended job during your next intimate time with the prized possession.

[jjgsxr1000 Junior Member Find all posts View Profile Close jjgsxr1000]

Filter in the A/C??
Im going digging!!!

Regards, Jay

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Sorry Jay but the 90's didn't come out with them, only the 120 upwards.

[Mark90s Junior Member Find all posts View Profile Close Mark90s]

I need to do my brake fluid and adjust the handbrake as the handbrake is almost non existent!?

I have a 97 grande. So is there a special way of bleeding the brakes as I'm used to opening the nipple while pumping the old fluid out on non ABS.

Apparently I need DOT3 fluid? Which sucks as I have about 5 bottles of DOT4 in the garage. Do I need genuine Toyota or can I go different?

Mark