Brake issues.

So here's the thing I have an 02 Jetta GLS TDI /w ABS, no ESP no TC.

For the better part of a year and a half a sequence of events has gone down.

Driver side rear caliper(original) seized, scored rotors and pads. Replaced

6 months later, happens again, same side and corner. Replaced all rear calipers rotors and pads, banjo line, the 6" middle hose, as well as parking brake cables. Issue still continued

Figured maybe the MC was part of the problem, had a sagging brake pedal as well...replaced that and the brake booster for good measure. Pedal somewhat OK now but still constant brake drag from the driver side rear...

Finally took it to a local shop, they tell me my front calipers are getting less pressure than my rear brakes, sounds like a proportioning valve issue, which I'm assuming is in the ABS Pump. They also recommended replace both front calipers and lines first to rule that out, though I'm not sure this will even solve the dragging issue.

IF it is a bad ABS Pump...what are the options for this?
Any way to repair/bypass it?
Can a used one be swapped in and reprogram that?

Not about to spend $1500+ on a whole new ABS Module on a 15 year old car. I'm pretty sure I should be looking for any corrosion on the brake lines too which I assume would be causing this as well but...yeah not sure which way to go from here.

Any help is appreciated, not mechanically savvy by any means and I don't know all that much but I do what I have to because I'm cheap lol

Dumb question, but did you grease the slides in your calipers?

I'd think you'd just need any soft coding if there is one and then use a pump from the same age car without the extras.

Pretty sure it's a rare problem too.

The sagging pedal is most likely air still in the rears, bleed them again after a week or two and maybe again after that to get any little tiny bits of remaining air out.


I wouldn't bother with the fronts unless the callipers were obviously stuck, usually when a flexi line goes internally the calliper sticks on because the fluid can't return.

Has the fluid been changed?
Theses cars do have bios to the rear brakes, that condition may be normal.
Seems like hardware or hydraulics would be responsible for the rear brake incidents.
There is an ABS bleed procedure which should have been done when you replaced the master cylinder.
Maybe find a more skilled mechanic, there is nothing unique about our brakes.

On a brake tester the fronts have WAY more pressure than the rears, somewhere around 300kg front and 90kg rear at my recent mot. I think it's the newer ones that use the rears more to prevent nose dives under braking.

Geobmx4life said:

Dumb question, but did you grease the slides in your calipers?

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Slick as a greased pig, they were redone every time I had to take off the caliper.

The sagging pedal is most likely air still in the rears, bleed them again after a week or two and maybe again after that to get any little tiny bits of remaining air out.

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The sagging pedal was only before I swapped the Brake Booster and MC

Has the fluid been changed?

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Yes, many, many times since this has occurred.

There is an ABS bleed procedure which should have been done when you replaced the master cylinder.

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I followed the procedure as far as bleeding goes using a Motive power bleeder, however I am void of any scan tool that powerful or VCDS to be able to cycle the ABS, though this doesn't seem to be an issue of air at this point as the car stops well and has a good pedal now.

UPDATE: So I was prodding around on my brake lines and noticed a bit of brake line corrosion around one of the fittings. I noticed the coating was peeling and the entire underside is white (galvanic corrosion?) plus the fitting is completely seized when I tried to loosen it, it just turned the brake line even after a lot of PB blaster and some hammering...

I'm going to assume this could be the culprit?

Since you changed the MC, do the VCDS flush when you get the opportunity, but yes that brake line could be the culprit.