# ABS Activation below 10mph



## sn34r (Mar 29, 2005)

I have a 2000 Jetta GLS 1.8t w/ 5-speed manual and I'm having a problem with my ABS (I think).
Whenever I come to a stop, as soon as my speed is below 10mph the ABS activates. I can feel the brake petal vibrate a bit, and the sound is exactly the same as when the ABS activates during a stop in icy conditions. Shortly after coming to a complete stop, the ABS deactivates.
I used my VAG-COM to monitor the wheel speed sensors and noticed that while braking 3 of the sensors have a nice smooth curve down to zero, but the front passenger side sensor drops right to zero as soon the vehicle's speed goes below 10 mph. Surely, this is what's causing the ABS to trigger; it thinks that wheel is slipping. But obviously the connection to that sensor is OK, because above 10 mph the speed registers correctly.
I've tried replacing all four wheel speed sensors, cleaning the hallway sensor area of the front hubs carefully, and recently replaced my control arm bushings, ball joints and tie rod ends. None of these fixed it.









Does anyone have a suggestion or something else to try?


----------



## sn34r (Mar 29, 2005)

*Re: ABS Activation below 10mph (sn34r)*

Update:
I logged the wheel speed sensors and graphed the data in excel. You can see clearly that something is wrong with the front right wheel speed.








The weird thing is, I replaced all the sensors about a month ago.
Any ideas what could cause this?


----------



## sn34r (Mar 29, 2005)

*Re: ABS Activation below 10mph (sn34r)*

@mods:
Is it possible to move this to the MK4 forum? No responses here is http://****************.com/smile/emthdown.gif


----------



## akid420 (Apr 23, 2009)

id try to go back even more a bit. the actual abs unit?


----------



## GTijoejoe (Oct 6, 2001)

*Re: (akid420)*

If that graph is the sensor's volt signal, than it should be a sensing/wiring issue. That would be the signal that the modulator is getting to react to, so because it is dropping out instantly it asumes wheel lock.
I would think because you replaced the sensors, that it's not the actual sensor. You can put that sensor on the other side and vise versa and I bet the same signal would appear. 
The signal does not drop out at the same speed every time, so I would think the chance of it being a software qwerk is low. 
How the signal jumps back in certainly does not look like a real ABS activation, the wheel can not instantly accelerate to the vehicle speed, so I wouldn't think its any type of hydrualic issue.
The only things I can suggest is a wiring issue, possible wierd grounding problem (which would not explain why it cuts out only at low speed), or you have a problem with the encoder ...possibly not giving enough resolution to the sensor at low speed to make the signal drop out.....








You should take another data log driving steady 35mph for like 2 minutes, see if the signal will drop out..... if it is consistantly drops out at low speed, at least you'll have a clue that it shouldn't be a damaged encoder.


----------



## sn34r (Mar 29, 2005)

*Re: (GTijoejoe)*

Thanks for the replies. I've tried driving around while logging the wheel speed sensors with a friend watching the graph and there were no weird dropouts or anything.
I'll check all the wiring this weekend, hopefully it's something easy like that.


----------



## Hablomos (Sep 27, 2007)

I'm having the exact same problem on my 2002 GTI. Just the same, the pulsing only happens at or below 10mph.


----------



## laloggia (Jun 30, 2009)

*Re: (Hablomos)*

Has there been a resolution to this problem? I'm having the same issue on my 2000 Jetta.


----------



## Anony00GT (Mar 6, 2002)

*Re: (laloggia)*

Check everything about the right/front sensor very carefully and thoroughly. Check the wheel that the speed sensor reads off of. Make sure it's tight and 100% intact, and make sure the air gap is correct and there isn't excessive rust or anything.
I've seen this issue in several makes and models (it's very common in 1500-series GM trucks/SUVs), and it's usually an issue of the relationship between the sensor and trigger wheel on the particular corner that's dropping out.


_Modified by Anony00GT at 4:48 AM 4-24-2010_


----------



## tropicdub (Mar 29, 2008)

*Re: (Anony00GT)*

im having the same problem to, right after i had my right front wheel bearing replaced it started doing this, i ordered a new speed sensor from german and im hoping this is it, because i think that the shop that i had press the bearing in pressed against the sensor, hoping this will work


----------



## twin2626 (May 11, 2006)

I helped my brother change his wheel bearing in his GTi and now his car is doing the same thing. He thinks its something to do with the distance apart the abs sensor and the sensor irng are. He tried bending the ring in and it helped a little but still does it every once in a while.


----------



## fugacity3 (Apr 21, 2008)

twin2626 said:


> I helped my brother change his wheel bearing in his GTi and now his car is doing the same thing. He thinks its something to do with the distance apart the abs sensor and the sensor irng are. He tried bending the ring in and it helped a little but still does it every once in a while.


I'm almost 100% that this is the case. I did the exact same thing on my 03 GLI - it always give a problem at


----------



## henitsl (Jul 11, 2009)

Exact same issue on my 2000 NB with 280K miles. Put on a new bearing/hub assembly on Saturday on my front left, and this happened. Activation under 10 mph. 

Last week I put in a new bearing and hub which was pulled out/pressed in by a VW dealer after I brought him the steering knuckle with the old bearing/hub assembly. I didn't have the tools to remove/install the bearings/hubs myself. 

About 50K miles ago, a tire shop put on new bearings only on this same car. Same problem back then with ABS activated below 10 mph. Took it back to the shop, and they made some adjustment. That fixed it. Now today I have the same issue. Must be the sensor distance or something. Will have to check it again


----------



## fugacity3 (Apr 21, 2008)

Glad your dealership could do some tweaking. Mine would only offer to redo the brake rotor and entire w/ new sensor ring for some obscene amount of money. They offered to do the cv axle since the boot is a little loose. Grand total was something close to $1000. 

Stay away from Suntrup in St. Louis.


----------



## fugacity3 (Apr 21, 2008)

And if anybody can get the gap tolerances from VW let me know.


----------



## Drhamgt3 (Dec 12, 2012)

*Check the Air Gap!*

I know this is an old thread, but just wanted to chime in and add some information for others that may be researching the ABS Activation below 10mph issue, as we just resolved this on my sons 2000 GTI yesterday. 
Check the air gap between the wheel sensors and the tone ring. 
After reading these forums, and after my mechanic told me he was "pretty certain" the problem was my ABS module, I asked him to "humor me, and check the air gap on the wheel sensors". Although he seemed a bit put off by the request, he checked it and found the air gap on the right front wheel was "significantly larger" than the gap on the drivers side. So, as recommended on the TDI Forum on this same topic, he took the sensor off, and ground down the brass bushing under the fastening bolt; to move the sensor about 2mm closer to the ring. Fixed it! 
MUCH cheaper than repairing/replacing the ABS unit as the mechanic originally suggested.
Thank goodness for these forums. Saved me $600+ on this issue. Hope this is helpful to someone else out there.


----------

