Brake bleeding problem - one line will not bleed

[timsch]

I can run the engine, but all of the other lines bleed just like I've always experienced them to without the engine running. It seems that it would be a consistent problem with all cylinders if this was the issue. I'll do it and get back with results

In all my time with cars over the past 25 years, I've never run across this. Unless manufacturers are using lower quality rubber, I too wouldn't expect this from an '08 vehicle.

 

[SHOZ]

It's probably a piece of rubber caught up in the hose. I would take the brake hose off where it connects to the hard brake line and see if the pedal goes to the floor.

 

[timsch]

I have now disconnected the hard lines from each the outer and then the inner flex hoses and the problem still persists, so it must be still further upstream. I then connected the lines back together, turned the engine ON, and had the wife press the pedal. The piston in the brake cylinder still will not push out.

At this point, the brake lines become harder to trace. I don't see any damaged sections of hard line.

 

[timsch]

Just to clarify, I did disconnect the steel line first from the outer flex line. With brake pressure there was still only a slight trickle of fluid from the steel line at this point. Then I disconnected another steel line further upstream from the 2nd (inner) flex line. Again, with brake pedal applied pressure, there was only a trickle of fluid initially from the steel line at this 2nd steel to flex hose connection. At this point, I have disconnected the hard lines upstream from BOTH flex hoses, so the flex hoses are not the problem.

 

[timsch]

I loosened the steel line from the ABS control module and had the wife apply brake pressure and the problem was just the same, slight bit of fluid initially, but then no more and the pedal never went to the floor. Retightened it and put everything back together.

So, I need to know more about the ABS control module it seems.

 

[Vikas]

Were you having problems with the braking system before you started on it? I have not followed it from the beginning but from what you are describing, you would have had problems in terms of your vehicle not braking and more importantly pulling to one side quite badly. Did you have those issues?

 

[timsch]

No noticable problems when driving it. With it being the right rear, it does not pull. If I hadn't been trying to replace the fluid, I never would have known.

That being said, I want to fix it. Even if I am at 90% stopping power, I don't want it on my mind.

 

[Vikas]

From all of your diagnosis, it seems that the problem lies inside the ABS unit or before it. You have pretty limited choices. Without the code, there is no way Toyota will cover it even if it were under the warranty. Without warranty, you are on your own to replace the ABS unit at a considerable cost.

You could have dealer use his Toyota Techstream scanner to bleed the system and see if the problem goes away first.

 

[timsch]

From all of your diagnosis, it seems that the problem lies inside the ABS unit or before it. ....Without the code, there is no way Toyota will cover it even if it were under the warranty. Without warranty, you are on your own to replace the ABS unit at a considerable cost./quote]

I'm afraid of that. If the problem were before it, I would expect it to affect all lines, not just one of four.

What code are you referring to? The ABS dash light does not stay on. If it were on, I'd check for codes.

I am hoping that it may be a problem with air inside the unit, and that a proper bleed may take care of it.

 

[Vikas]

Check with TheCritic to see if Toyota TechStream allows ABS bleeding on demand and how long should it take. Based upon his answer, you can take it to the dealer ask them to perform that service. You should also have an idea of what would be fair amount of labor charge for it. It is also possible that once you pay the dealer his "cut" of your flesh, he might later be little bit more inclined to bat for you towards Toyota zone representative to get you new ABS module.

If you are not getting adequate flow/pressure to one wheel, you should be able to measure the effect of it objectively. For example, you could compare the friction material i.e. pad usage between the two sides or better how the brakes grab differently between the two sides. Take a stick and wedge it between the brake pedal and the driver seat and try to rotate the two sides and see if you can feel huge difference between them.

I am sure you can come with more ideas. But if you can not objectively demonstrate the problem, you need to forget about it.

 

[Trav]

Someone has to have one of these, maybe the dealer? Most European shops doing brakes have to have one. How else can you really test the brakes?

Doing a brake job without properly testing them is really iffy.
IMO it should be mandatory.

 

[seascott]

You probably have air between the master cylinder and the ABS module. Fix is probably a pressure bleed from the master cylinder to get all the air bubbles out. Let Toyota or another trusted mechanic try it first before replacing the ABS module.

 

[The Critic]

This is the factory bleed procedure; I believe the 05 and 08 Siennas are the same.

http://www.justanswer.com/uploads/snd27613/2008-09-16_200152_sienna_brake_bleed.pdf

Does your van have VSC? Using Techstream to bleed the brake actuator may be something to look into.

 

[Ken2]

When the dealer's service writer writes you up for a full brake job, tell him to SHOW you why it needs that. Of course it doesn't, but put the lazy slacker on the spot. (Do service writers get paid on commission?)

 

[SHOZ]

ABS pumps have normally open valves When the ABS is activated it pulses the valves shut Sounds like one of the valves may be stuck shut. Try giving the ABS pump a good whack near the brake lines Maybe it will pop open?

 

[timsch]

Thanks everyone for the many suggestions. I plan on getting back to this issue this weekend. I have a gravel road nearby where I can go give the ABS control module a workout. Perhaps before I go I will tap around on the module to free up anything that may be stuck. Air may be an issue and if so, hopefully this workout may purge it from the module.

My 2008 Sienna does have VSC. I'll look into the Techstream. At 1st glance, it appears to be a bit steep for purchase. I'll try to find a shop to test it for me if I don't buy it.

 

[Vikas]

If you are willing to "look the other way", I have seen Techstream "fallen off the truck" being sold on ebay for cheap prices.

 

[timsch]

I took the sienna out to the dirt road and gave the ABS system a serious workout. Did about two dozen hard stops and the system performed decently, although not consistently. 80% of the time it held a straight line, but the other times the rear would slide out to the right, as could be expected with the right rear not braking. This could have been the camber of the road causing this, but the front did not tend toward the right at any time.

I got back and nothing had changed. I had the right rear jacked up with the wheel spinning freely. No fluid when trying to bleed. Also, I could still spin the wheel when the brake pedal was pushed.

Back at the ABS control module, I verified that when the brake pedal is pressed, fluid will flow from any of the other three brake line connections when I break the seal, but not from the ABS control module port, even with the line fully removed.

I wonder what self-diagnostic test is performed at startup on this module, because I have no lights indicating a problem.

I have not found a shop to take it to yet for the Techstream. I did find knockoffs on Ebay, which seem to have found a pretty good following, but have not ordered that or anything else yet.

 

[Vikas]

Quote:
because I have no lights indicating a problem.
Does the indicator bulb work? You should see that lighted up before going out when you give the ignition.
Quote:
I had the right rear jacked up with the wheel spinning freely.
You have a real problem. You should be able to demonstrate this to a shop or better to the dealer. I am afraid that this looks like internal blockage inside the ABS unit and if your multiple attempt at ABS braking has not undone the blockage, I suspect the Techstream will not be able to do it either. If the dealer is not cooperative, you might want to open a case with NHTSA as this a pretty serious manufacturing defect/safety issue and should not be occurring on a relatively newer vehicle.

 

[timsch]

Indicator lamp does light up when ignition is turned on initially.

I again verified that the lines are clear by pumping brake fluid from the end of the hard line that attaches to the ABS control unit with a MityVac pump. It flowed out the bleed valve as expected.

Yes, I'm certain that the problem is in the ABS unit. I have still some hope that perhaps it is related to air inside, but that is only a hope.

A trip to a shop is next. I certainly hope that the Techstream tool will be able to tell a competent mechanic what the actual problem is inside the control module. I'd be sorely disapponted with a "Yep, looks like the control module is broke...." diagnosis. I'll try to find an independent mechanic before taking it to the dealer. The only problem with that is that I do all of my own work on my vehicles so really don't know who to take it to. I'm in the Houston area, so I know that there are some good ones around. Just have to find one....