Guys,
I figured I'll ask this question here since the lexus forum is of not help in this matter.
Given ABS technology is kind of the same with perhaps different brands perhaps I'll have better luck getting this answered here.


1993 Lexus LS400
problem: spongy pedal, not so effective brakes.
the brake problems all go away after I engage the ABS or traction 3 or 4 times manually. the pedal feel and the bite in the brakes remain for a day or so and the pedal goes back to spongy, extra pedal travel and loss of brake bite. I have to keep on activating ABS by driving in reverse and hard hitting the brakes to keep the brakes at their optimal.

parts changed so far:
brake booster
master cylinder
all the callipers greased
brakes bled several times, last week got the ABS system bled by the dealer

no change at all.
One of the private shops suggested that the ABS pump could be the cause of this problem. However the Lexus dealer said that the ABS doesn't come into action unless ABS is activated. The private mech. claims that with this system the braking system at all times has to travel through the ABS pump which in turn sends the brake fluid to the 4 wheels.
quesiton is, can the ABS pump be causing this ? If someone has a diagram of the system perhaps they could post this here. I would like to make sure this coudl be the cause before investing 1750 in the pump and 5 hours of labor.

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.

I don't know ABS systems from beans but there might be a faulty check valve or a reservoir or accumulator in the ABS innards that bleeds down when the ABS hasn't been engaged for a while.

Sixto
95 S420
87 300SDL

Here's an article that I've found pertaining to the situation I'm experiencing.
http://www.babcox.com/editorial/bf/bf50434.htm
It refers to "lock lines" that I am not able to find at the local stores. Most of the lock lines I've found on the net are lock line kit's that hold the brake pressure allowing you to take the foot off the pedal. mostly for 4X4 use.
I, however, am looking at plugs that would fit/screw at the outlets of the M/C and also at the individual brake components to isolate the problem areas. they're called lock lines as well but are kind of different.
for those who don't know what I'm referring to there's a picture of those lock lines in this article.
http://www.babcox.com/editorial/bf/bf109954.htm

At this point, I want to know if there's anyone who has troubleshot the brake system taking the route described in the two articles. I've pretty much been to all the shops in the NJ area and everyone's given me a simple NO answer. That's a shame that the owners have to spend money on expensive brake parts because the shops just don't know how to troubleshoot the braking system properly.
The only shops that I can think of that are the shops who build the hotrods from ground up. Since they install all the components themselves I'm sure they would know what they're doing.
any comments will be appreciated.

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.

i can use some help here

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.

Check with your local Snap On tool dealer for tool #YA2850 . You can see these on the Snap On online tool catalog to see if these will work for your application. Hope this helps, Robert.

__________________
Mercedes Benz Master Tech - Retired

So I'm interested and got some time. I went to a tech site (techs only) and I'm looking through fixes and I came up with one I'm going to paste here. Then I'll look for some more and paste them too if there are any.

I debated whether to put the last line into the paste. Thought I might since I see the absolute opposite attitude here constantly:

After more
investigation of the brake system We find a frosen caliper
pin on the left front. It was so bad that even after heating
the bracket and soaking it with penetrating oil the slide pin
did not loosen up We replaced the caliper It fixed the spongy
pedal and brake affect is normal Oh I did ask costumer if he
had felt the pedal soft before He said someone told fim it's
becouse the car needed rear pads He did'n mentioned it
becouse I olso told him the rear pads were worn out This is
how The EVER SINCE YOU FIXED MY CAR claims start!!! One more
client that knows We are not MIND READERS

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Two more down the page and here is a back-up, never would have thought:

Found a siezed caliper slide pin,cleaned and lubed all
slides.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

I am no expert but what about the booster?

Iggy

PS I see that you changed the booster, are you sure it was correctly installed? What about a vacuum leak somewhere along the lines that causes the booster to fail a little or have problems?

Another thought - have you checked the hoses? Maybe one of the hoses has a bubble. When you pump the brakes it expands therefore causing the spongy feeling?

__________________
Insanity: doing the same thing over and over again and expecting different results.

2006 - Suzuki Gran Vitara (2.0 L fully equipped) Like this car so far except for trying to put on the seatbelt.
1988 - 190e - 2.3L - 172K miles (It now belongs to the exwife)
1999 - Chevy Blazer LS Fully Equiped - killed it June 2006
2001 - Honda Civic EX - 68K miles (sold June 2004)
1963 - 220S - Dual Carb 6 cyl. (sold)
1994 - Yamaha WaveRaider (fun to ride)

I didn't read this whole paragraph because I got tied up reading the first link. While I have done such testing, I have to point out the shops side of your problem.

The most important part of the shops side of the problem is that it AIN'T their problem. If that part was clearly understood by the vehicle owner, one could sure find a big improvement in technical capabilities.

In the posts I found above two techs solved your problem on two separate Lexus cars, one a 94 LS400, the other a 92 ES300. I guarantee they weren't paid properly. What you are asking for is technical research and you probably want an estimate. The answer you get is due to the conditions of the venture.

Are you willing to pay, without an estimate, for a good tech to figure out your problem. What will you say when the guy finds a stuck caliper guide pin after ten hours of systematic testing that you wish. The pin costs 3 bucks, are you ready for $750 in labor, no way the bums a crook. Us techs know the way you (retorical you) are. Do you think we want such jobs knowing we will get screwed. What.. ten hours labor, you must be one dumb tech. Who needs it.

I spend my whole life doing such testing and diagnosis, I need 7 techs doing menial labor to afford me being able to do such. There is no money in such work, only fun. Fun don't pay the bills.

The whole of the automobile repair trade is really lost, because no one in their right minds would pay for what is necessary to fix 5- 10% of the repairs we see. In my case I can still do it cause my half million dollars in tools are paid for and I am too stupid to require a ROI. I don't even make money using them, but I do keep customers cars on the road so others can do waterpumps and brake pads enough to keep my doors open.

The chances of finding a similarly stupid well equiped tech who is subsidized by regular work is unlikely, as you have found. Donate your car to the lead tech at any shop you have been to and it will be fixed next week.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

steve,
thanks for the replies.
just to coment on the fact where the labor is concerned regarding the troubleshooting, and to mention that i didn't play 'cheap' trying to figure this out here's what has been spent on the car since the last year trying to figure out this problem. the price includes both the parts/labor and all are at the dealer with the exception of the extra brake bleeds that i had to take elsewhere on top of paying the dealer just to make sure there wasn't air in the system.

intial diagnosis 2hrs : 196
change m/c : 650
further diagnosis : 98
diagnosis charge 2 months later : 196
change brake booster: 1570
diagnosis : 98
three brake bleeds : 266
diagnosis charge: 98
change rear calliper: 400
bleeding of the system for ABS ( i was told this is different that the regular bleeding) : 98
ABS light came on therefore diagnosis of ABS : 196
ABS accumulator and hose change : 870
the $870 charge is only two weeks old.

I don't even want to add this all up because that will just make me sad. I have receipts for all the above and can even scan and paste them to prove it.
All of the above, only to fix a spongy pedal which is still the same as day one. nothing, I mean absolutely nothing has changed even after everything they have replaced above.
So in defence of the statement I made where I said that it'ss a shame where the owners have to spend money on "expensive"parts because the shops just don't know how to troubleshoot the system would be kind of valid.

the sliding pins were also addressed by the shop. atleast I've been told so. the shop stated that they greased all the pins and make sure that there was proper sliding and that that the pins were straight.

the spongy pedal is not like that 100% of the time . If I engage ABS myself by driving it in reverse and slamming the pedal, the spongy pedal goes away instantaneously. perfect braking for the rest of the day or so. but then all of a sudden it goes back to the old spongy ineffective pedal with increase travel as well.
Steve, I've read most of your articles regarding your shop and the tech tips that you've posted. If you're willing to take this up as a challenge, I would be glad to arrange of shipping of the car to your shop. granted that might cost around 1600 just in shipping charges, I am willing do to that after spending the thousands already to fix it. but keeping in mind that it's a lexus and not a benz and I'm not sure if you fix that brand. but then again perhaps there is a brake shop in the east coast where they can charge me to troubleshoot rather than just throwing parts at it. At this rate I'll end up spending more on the car than it's worth. ..

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.

Your original paragraph that I wrote about made me think you had tried all the techs in NJ. If your list of charges is from one store then you have a real gripe. if you have moved from place to place then you haven't given any one the chance to do the deep dig required.

My commentary is based on the concept that a techs time is only worth something if he provides results. Unfortunately this is the culture of auto repair. Take the smartest tech you want and evey once in a while he will spend a great deal of time with ambiguous results. if he were less of a tech he would be putting water pumps on and take no risk. Think about it, try the same attitude on the medical community. Only pay for results. What? the doctor practiced on me and I died and he wants to get paid... the nerve.

The culture breeds the problem you have whether you are a part of it or not. Other than shear fun why else would a tech take on a challenge.

BTW, I'm rather knowledgable in Mercedes repairs. I'm just another tech when it comes to Lexus. While I'm sure I could fix it (find me a tech that thinks he can't and I'll show you a parts replacer), I tend to avoid long range diagnstics for two reasons. First I have limited ability to follow up and second even though I love the challenge the businessman in me knows I do not need to buy any problems that don't bring me water pump repairs.

In other words, I only attempt hard diagnostics for current or future long range business from a business sense. I am fully aware that the kind of problem you have can eat ones lunch and no reason it should be mine. This last part is the point I wish to make in this forum of technician bashers.

Part of my problem is that in my shop you only pay for diagnostics once per complaint and the final repair even if drawn out only includes the price to do the one repair necessary once. I might have to put that old booster back on and I WOULD charge for the labor as diagnostics but I would eat the impoperly diagnosed parts.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Robert,
thnx ! that's exactly what I was looking for. I'll order them. strange thing is that after going to autozone, advance auto parts and pep boys along with calling others in the area no one had even heard of these. and the brake shops denied there's even such a thing in existence !

Steve,
the work was all done at the lexus dealers. two to be exact that are in central jersey. but for diagnosis I've taken the car to alteast 10 different shops and paid them as well. with everyone ending up doing a bleed and then just saying they don't know what else to do !

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.