# Brakes grab weird then ABS lights pops on? please help.



## wes702 (Aug 24, 2009)

Kinda hard to explain but hear goes...
some days i turn on my car and drive for awhile and everything is fine. other days i turn on my car and my ABS light is on right away. then there the days ill drive for awhile and go to apply the brakes and about half down to compressing the brake pedal all the way it feels like my brakes grab REALLY hard, at times its so bad i almost lock up my brakes, very weird feeling. other times ill hear almost likes a "pumping" sound coming from right behind my fire wall near my feet then my abs light will pop on. when it does this when im not pushing the brake pedal its almost like my brakes grab a little on there own. the routine is never the same, i've gone days without anything everything ever happening. it doesnt seem to differ on the way im driving either. or with different weather conditions. could it be an air buble in my brake line somewhere? bad ABS pump? any ideas please let me know, thanks. by the way, my car is a 95 jetta vr6.


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## krymson (Jul 6, 2009)

*Re: Brakes grab weird then ABS lights pops on? please help. (wes702)*

I'm experiencing this problem as well. ABS is on mysteriously, and sometimes pumps my brakes when I'm braking inexplicably. Just started doing this two days ago.


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## wes702 (Aug 24, 2009)

*Re: Brakes grab weird then ABS lights pops on? please help. (wes702)*

Anybody have any ideas?


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## GTijoejoe (Oct 6, 2001)

*Re: Brakes grab weird then ABS lights pops on? please help. (wes702)*

Does this vehicle have other modulator functions other than ABS?
VSA, TCS, EBD?
I would say 99% of the time you have a faulty ABS sensor signal, and than 0.9% of the time your modulator's module is screwy..... 0.1% for all other issues like dirty circuits or fuses etc.


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## wes702 (Aug 24, 2009)

*Re: Brakes grab weird then ABS lights pops on? please help. (wes702)*

a friend of mine said that it could be my ABS pump, could this be the problem? if so how would i check to see if it really is the problem?


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## GTijoejoe (Oct 6, 2001)

*Re: Brakes grab weird then ABS lights pops on? please help. (wes702)*


_Quote, originally posted by *wes702* »_a friend of mine said that it could be my ABS pump, could this be the problem? if so how would i check to see if it really is the problem?

I gave you the info that you are looking for, and you neglected to answer my question.
ABS 'pump = modulator in general... this unit has more functions than just 'ABS' which is why I won't refer to it as an ABS pump, in addition too the ABS 'pump', the pump is actually a part of the modulator. 
There is a very very slim chance it is the actual pump, but the module, the ECU's brain which has all the solnoids can go bad, my 0.9% suggestion. If this goes bad, normally you will flip a code, the dealer will be able to tell you if this is bad.
I'm betting that you have a faulty ABS sensor signal. If the ECU thinks you have different wheel speeds and has TCS, or EBD or something similar which will allow the modulator to apply pressure (unlike ABS which releases pressure) it will brake your calipers. 
Are all of your tires the same size? You can measure the resistance of your ABS sensors, just unhook the harness, usually if they are all not the same, than you can find the faulty one. You can also check all of the ABS pick-ups on the hubs be sure there is nothing in them causing a miss signal.
In addition you will not always throw codes on ABS sensors, only when they fall completely out of the measured spec the ECU is looking for.
GLuck


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## wes702 (Aug 24, 2009)

*Re: Brakes grab weird then ABS lights pops on? please help. (GTijoejoe)*

sorry about not answering your question, thank you for the help, im doing new rotors and pads on all 4 tomorrow, ill check everything to make sure everything is clean and hooked up good. and yeah all 4 tires are the same size and same model, although now that you mention tires..... now that i think about it this problem started right after i got new tires put on at costco (about 5k miles ago) could they have messed something up? thanks agian for the help.


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## GTijoejoe (Oct 6, 2001)

*Re: Brakes grab weird then ABS lights pops on? please help. (wes702)*

Only if they damaged something in your wheel speed sensor area...
Tires won't have an affect unless they are different diameters...


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## wes702 (Aug 24, 2009)

*Re: Brakes grab weird then ABS lights pops on? please help. (GTijoejoe)*

gotchya. well i just finished rotors and pads, drove around, still got the problem. i noticed now when i hear that noise by my feet behind the fire wall and im not applying my brakes and just costing, my car actually slowes itself down considerably, its like my brakes are working on there own. then i give it gas and i can tell my car is slower, i have contant brake pressure.







so frustrating.


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## GTijoejoe (Oct 6, 2001)

*Re: Brakes grab weird then ABS lights pops on? please help. (wes702)*

How about when you put the car in neutral and coast still same?
Unplug the modulator's fuse to turn it off, and see if the problem still exists.... or you can also unplug one of your ABS sensors, that'll put the ABS system in fault and turn it off too.


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## less.than.jeff (Sep 2, 2008)

*Re: Brakes grab weird then ABS lights pops on? please help. (GTijoejoe)*

I have this same problem and was doing some research on it.
I saw in another thread someone cleaned the wheel speed sensor because it was completely GUNKED OUT. I'm gonna try this tomorrow, you should too before you consider forking out money to a mechanic


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## wes702 (Aug 24, 2009)

*Re: Brakes grab weird then ABS lights pops on? please help. (less.than.jeff)*

yeah i replaced my rotors and pads last week and cleaned the gunk off the best i could but there is still alot i couldn't get off (14 years worth). i think ill try and use maybe some really stong degreeser and a pressure washer or maybe just have my undercarage steam cleaned.


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## less.than.jeff (Sep 2, 2008)

*Re: Brakes grab weird then ABS lights pops on? please help. (wes702)*

Ok so today started with my ABS light on. Just took off the two front wheels and cleaned the gunk off the sensors (LOTS OF GUNK). [Haven't checked the back sensors yet] I also noticed metal shavings in between the magnetic sensor and the rotor causing a connection between the two which in turn flips the abs light on. 
Cleaned it out the best I could and drove around my neighborhood, 30 seconds later light went off!







fingers crossed


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## Strikethebox62 (Sep 14, 2010)

*ABS issue.. 95 Jetta GLX*

I am the current owner of wes702's mk3, and i am still having the ABS issue even after i had the Module replaced, however i can get the brakes to operate properly after turning off the car and restarting it once the abs light comes on... any input to what the problem might be?


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## Strikethebox62 (Sep 14, 2010)

BUMP!


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## Strikethebox62 (Sep 14, 2010)

bump! still having this issue... considering abs delete.


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