ABS acting weird

[jonlowe]

2005 Passat Wagon, GLS with ESP.

Sometimes at very low speeds, such as pulling into or backing out of my garage, and near the end of stopping at a traffic light, I can feel the ABS system kicking in, pulsing the pedal. This is on dry pavement. I recently had to have the outer CV boots replaced, and this issue seemed to start after that. A VCDS scan shows nothing amiss, and no lights come on.

From what I can tell, this could be caused by dirt between the ABS sensor and the notched wheel. Does that make sense? Anything else I should look for?

Jon

 

[Seatman]

This usually means a sensor is on its way out but in the case of the passat that might be different. The sensors in the front hubs of the passat are just pushed in as far as they go then pulled back a tiny fraction. There's no bolts or anything holding them at the right place. I suspect either one has taken a knock when the cv's were swapped or someone has damaged one of the reluctor rings which are on the cv joint I believe.

 

[jonlowe]

I plan to pull off the front wheels tomorrow and take a look. I checked ELSAwin and ETKA, and I'm not sure if I have both an ABS sensor and a traction control sensor, or if the traction sensor does both. I found a diagram that shows the sensor going in the back of the front hub, just pressed in as noted above, and another going in the side, bolted. Anyone know for sure what I should be looking for?

Thanks for the info.

Jon

 

[Alchemy]

Are you sure that they just replaced the boots not the entire axle assemblies? I had a place tell me they replaced the boots, when in reality they put in some junky aftermarket imported crap axles (not just the boots) in and the trigger rings were loose on them. I reset and cleaned the sensors, but in the end the only cure was to put OEM quality axles back in.

Look for the VW Part numbers on the axles in your car now. If they are not there, you may have found your problem.

 

[Seatman]

I plan to pull off the front wheels tomorrow and take a look. I checked ELSAwin and ETKA, and I'm not sure if I have both an ABS sensor and a traction control sensor, or if the traction sensor does both. I found a diagram that shows the sensor going in the back of the front hub, just pressed in as noted above, and another going in the side, bolted. Anyone know for sure what I should be looking for?

Thanks for the info.

Jon

Same sensor does both usually, odd set up though, just this metal sprung loaded thing the sensor goes in with. Not sure what the other thing was you seen but you can post those diagrams up as a pic then we can see what you're on about.

 

[Uberhare]

It is possible they damaged the ABS ring when doing the CV service. Both the rings were damaged on the shafts I received from Europe for my 6 speed swap. I knocked the originals off and press them back on. I still get a bad low speed reading on the front right sometimes. Just haven't had time to take it apart....10K later now!

 

[jonlowe]

Pulled the sensors from their sockets, cleaned the ends off, pushed them back in, and no more problems.

BTW, I confirmed I do have VW axles.

Thanks for all the suggestions.

Jon