ABS brake issues

trust · Post by **trust** » Thu Jul 10, 2008 9:10 am

My daughter has a 2000 jetta tdi, the brakes have been weird for a while recently when warm outside, the weather, not the brakes, they will drag, sometimes quit badly. Only the front it seems. I now have the car and in the past few weeks it has gone from dragging to something new and very weird. if I just cover the brake pedal ever so lightly the brakes will self apply, I can feel the pedal pull away from my foot! then, randomly, ther will be a distinct pressure release when I do apply the brakes and they will work somewhat normally until the next time I touch th epedal, if it is light they self apply if i brake with any force at all I get normal response and the sudden pressure release.

It shows no trouble codes and the local shop has taken a look and believes it is the ABS controller, quoting a $1500-2000 parts and labor repair. I've not found the ABS controller available anywhere yet, i just started looking though, and assume it's a delaer item?

Any thoughts? if I can find a controller how bad is it to replace?

thanks

trust · Post by **trust** » Tue Jul 22, 2008 5:14 pm

a new development; it has begun to moan in various tones and volumes whether the brakes are applied or not.

JRM · Post by **JRM** » Wed Jul 23, 2008 12:46 am

im not expert, but i had a simular issue on my toyota when i bought it used- it turned out to be that the previous owner replaced the front brakes and never let out the extra brake fluid causeing massive pressure buildup when warm, the hotter it got the more the brakes drug. Its to bad it took me a few weeks to figure it out, the hot dragging brakes cooked my rotors and all berrings, seals and outter front cv boot- I opend the bleed valve and whoosh, pressure was let out- i blead them all correctly and lowered the fluid level down to max and its been perfect since.

82vdub · Post by **82vdub** » Wed Jul 23, 2008 9:05 am

JRM wrote:it turned out to be that the previous owner replaced the front brakes and never let out the extra brake fluid causeing massive pressure buildup when warm

That's a new one for me. This would mean that fluid would need to be added to the system as the brakes wear, and that no fluid travels back up the brake line to the master cylinder when the brake pedal is released. With that much pressure, it would seem that a person would not be able to compress the caliper to get the assembly onto the new brake pads and caliper bracket, if there was that much pressure in the line. At least that's what I get out of this. Not saying it didn't happen, but definately weird, and a first for me.

JRM · Post by **JRM** » Wed Jul 23, 2008 10:38 pm

yup, it so full when i unscrewed the resivor cap fluid blew out of it- and yes the previous owner ( my x's husband ) did spend a hour prying the pistions back and to get the new pads in- it was a costly mistake that i had to foot the bill for

trust · Post by **trust** » Thu Jul 24, 2008 3:42 pm

hmmm, thanks for the input, I will go take another look but I have tried to rebleed the brakes just in case it was a fluid issue but I can do it again. did yours moan and groan? it's often embarassing to be stopped at teh light and hear this terrible noise, or set of noises, emit from the car

thanks!

82vdub · Post by **82vdub** » Thu Jul 24, 2008 5:31 pm

It very well could be the ABS controller. Have you tried another shop or two to see what they're diagnosis is? That may be the quickest way to find an answer.

JRM · Post by **JRM** » Thu Jul 24, 2008 9:08 pm

sounds like the noise you are hering is the abs system working as if its sensing wheel lockup- but if your stopped thats normal so a controler or a sensor has gone bad. Does your speedo read zero when stopped?

trust · Post by **trust** » Mon Jul 28, 2008 5:05 pm

Thanks all, I haven't tried another shop yet, we actually don't have two decent ones here in town but I'll take it in to another one for a diagnosis only and see what they say. Is there a way that I can tell if its a controller or a sensor? A buddy found an 03 in the pic a part that has the controller intact so I may hit the yard next time I can get to town and pull it if poosible.

I think the speedo does go to zero but I am not sure, I'll pay attention tonight.

thanks all!

trust · Post by **trust** » Tue Jul 29, 2008 4:20 pm

checked and yes, the speed-o does go to zero as it should

can anyone verify that the 03 controller (the pices with the lines in and out) is the same between 2000 and 2003)?

thanks again

82vdub · Post by **82vdub** » Tue Jul 29, 2008 4:47 pm

trust wrote:can anyone verify that the 03 controller (the pices with the lines in and out) is the same between 2000 and 2003)

If you call a salvage yard, they should be able to tell you what years will interchange.

trust · Post by **trust** » Mon Aug 04, 2008 3:51 pm

thanks, i'll verify before I pull the one out of the wreck

trust · Post by **trust** » Wed Aug 13, 2008 5:13 pm

Ok all, I did find an ABS controller in a salvage yard, very easy replacement (relatively speaking) however it did not solve the problem(s). I am now thinking that the groaning is non brake related, and that the sudden pressure release must be from the booster. Thoughts? I have disconnected the vacuum source to the booster and everything seems to be OK so far other than a stiff pedal. Any problems with this? I think that if I can get a few miles in the heat of the day like this and do not have either of the issues (still the moaning but that may be PS or???) then replace teh booster. Sound logical? In looking through the bood there is a specialty tool need to release the pedal from the brake push rod, really need it or is ther an alternative?

thanks for the help thus far, hopefully we're getting close