ABS "Farting" when stopping

rshelor · May 30, 2011

OK, I've cleaned sensors, taken to local reputable wrench who found no scan faults or anything to indicate the cause. Anybody have similar problem? How about ground to module issue. Similar thing on my Silverado turned out to be the ground to the unit.

History:
ABS light came on and replaced sensor w/front wheel bearings. Light went out, but farting did not stop.

Any way to defeat ABS w/o triggering dash light?

roadhard1960 · May 30, 2011

I have no experience but here is a question or two. Have you bled the brakes using the VagCom ABS procedure? Have you scanned with a Ross-Tech cable and software?

rshelor · May 30, 2011

Abs

I don't think its an issue of bleeding as the trouble started during a sand storm in AZ. ABS light went on and went off after installing a new driver's side sensor. The "farting" issue began then and did not end w/new sensor. Brakes were bled three or more months before during clutch change by good wrench worker, so don't think I can hang it on them unless its a delayed affair. Logic would make one suspect the new sensor, but scan says no problems there.

The same good wrench did the scan and I have no idea what he uses.

FL/COtdi · May 30, 2011

The first time I had to slam the brakes the car felt very different. I reason that the ABS brakes rapidly lockup and let go very quickly. Sets up a funny vibration that could be considered farting? No CEL at that time, though.

rshelor · May 30, 2011

Abs

No this is the ABS operating when ever I come to a slow stop. Not all the time, just often enough to really get under your skin.

Matthew_S · May 30, 2011

Use a scan tool to monitor all four wheel sensors. When you come to a stop one of them is probably dropping to zero at low speed. The ABS computer will see this as wheel lock up rather than a sensor malfunction and will activate the ABS rather than set a code.

Seatman · May 30, 2011

I think you might have a sensor on it's way out, I had the exact same thing and eventually the abs light would come on and go off randomly but it turned out to be the right front sensor packing up, I replaced that and everything has been fine since. You could also check the condition of the reluctor rings but i would expect more dramatic effects from that in my experience.

rshelor · Jun 1, 2011

Abs

Matthew_S said:
Use a scan tool to monitor all four wheel sensors. When you come to a stop one of them is probably dropping to zero at low speed. The ABS computer will see this as wheel lock up rather than a sensor malfunction and will activate the ABS rather than set a code.

Mechanic used scan tool and found nothing from any wheel.

rshelor · Jun 1, 2011

Abs

Seatman said:
I think you might have a sensor on it's way out, I had the exact same thing and eventually the abs light would come on and go off randomly but it turned out to be the right front sensor packing up, I replaced that and everything has been fine since. You could also check the condition of the reluctor rings but i would expect more dramatic effects from that in my experience.

You probably are correct about the sensor. I don't know what the life expectancy of them is. When I replaced front wheel bearings I replaced the bad driver's side sensor and cleaned up rear sensors and inductor fins. Like I said, the light went out, but not the triggering of ABS. If I feel like throwing money at it I will probably go with passengers front sensor.

Seatman · Jun 1, 2011

Just give it time, I'm fairly sure it'll throw a code soon, mine went on for ages without a code or that, I kept cleaning it but eventually the light would come and go then I got a code so just changed it.

Ski in NC · Jun 1, 2011

Look at gap between sensor and tooth ring. If too far away it will lose signal at low speed.

turbocharged798 · Jun 1, 2011

You need to use VCDS and scan the ABS controller for fault codes. If that is clear, then you can monitor each wheel sensor to see what speeds it reading. Maybe one sensor is giving a false reading and is confusing the pump.

rshelor · Jun 2, 2011

Ski in NC said:
Look at gap between sensor and tooth ring. If too far away it will lose signal at low speed.

That is something I considered, seeing as I replaced wheel bearings, but it should not have changed the gap. Any idea to what the gap spec is? Thanks to all. I would be a happy person if the machine would throw a code, otherwise its all a big guess. But until then, outside of an excessive gap between sensor and inductor ring, I must live with the intermittent problem.

Seatman · Jun 2, 2011

Bloody close lol, that's the official gap required

Matthew_S · Jun 3, 2011

rshelor said:
Mechanic used scan tool and found nothing from any wheel.

No codes or he drove around monitoring the speeds and they were all normal? A faulty sensor won't necessarily set a code.

Seatman · Jun 3, 2011

You could check the ohms reading between left and right front, I remember mine was way off compared to the new one I bought.

rshelor · Jun 6, 2011

Abs

Seatman said:
You could check the ohms reading between left and right front, I remember mine was way off compared to the new one I bought.

Thanks Seatman, That is some advice that I can actually do myself. I will do as soon as I have a few minutes. Each should read the same I suppose, but we'll get to the specs for a good sensor later. Thanks again. Hoot Mahn!

rshelor · Jun 7, 2011

ABS Problem

Matthew_S said:
No codes or he drove around monitoring the speeds and they were all normal? A faulty sensor won't necessarily set a code.

He said he drove it all over the place with scan tool and nothing showed. Would the wheel w/the bad sensor be detectable when stopping, or do all the wheels get pulsed when the ABS triggers making individual detection impossible?

kmicinski · Jun 24, 2011

I have this exact same problem that just started the other day. My drivers side rear parking brake cable was sticking and it wore out the pads and rotor. I was going to change them but I guess I let it go to long because I went around a turn and hit the brakes hard and my low fluid light kicked on for a second because the pad was so worn out all of the fluid was back there. I went ahead and got the pads and the rotors changed that same day but ever since that hard brake pedal I have also had the slight abs flicker right as I am rolling to a stop. I just cleaned the rear induction rings and checked all of the clearances so I don't think it is that for me. I guess I will try ohming them out next and see if I am getting a faulty sensor even though I have no code either.

rshelor · Sep 21, 2011

Fart

Ski in NC said:
Look at gap between sensor and tooth ring. If too far away it will lose signal at low speed.

Yep, too much space. Bently gives the distance, but I don't have it in front of me. Something to the tune of a mm. I replaced front wheel bearings and new ones must not be identical, though I put a digital caliper to them and they read the same. The fix was to bend the rotors in with a set of channel locks.

73veedubya · Sep 21, 2011

i get this from time to time also...but at this point i need new suspension stuff an every thing so its prolly adding to it all..

BakoTDI · Aug 30, 2018

same problem

Sorry to revive this thread but I came across this:

https://forums.vwvortex.com/showthr...dal-gives-in-with-slight-grind-clicking-noise

I also found this in my manual...hope it helps someone. I gotta check mine.

scurvy · Aug 30, 2018

My Golf has been doing the same thing for about 4 years now. It's a wheel speed sensor that's slightly too far away from the tone ring. You can look at their values in VCDS to find out which one isn't reading correctly.

FWIW the wheel speed sensors should measure 1.0 - 1.3 kΩ and 0.3mm (0.012") away from the tone ring.

KrashDH · Aug 30, 2018

My Golf is doing this with an aftermarket sensor I put on. Only does it at slow speeds turning in 1 direction. It's definitely a gap issue. Thing is it won't go in any further. Trips the ABS when I'm going very slow turning into a parking spot then hitting the brakes

scurvy · Aug 31, 2018

KrashDH said:
It's definitely a gap issue. Thing is it won't go in any further.

You have to file down the mounting ear to push the sensor end further toward the tone ring. Stack up of tolerances of the steering knuckle, wheel bearing, hub, etc... means it's tough to have it fit correctly right out of the box, especially if it's an aftermarket installation. My wheel speed sensor is OE but not OEM as well, and it needs a little file-to-fit touch up.

0.3 mm or 0.012" is the specified distance between the tone ring & sensor.

KrashDH · Aug 31, 2018

scurvy said:
You have to file down the mounting ear to push the sensor end further toward the tone ring. Stack up of tolerances of the steering knuckle, wheel bearing, hub, etc... means it's tough to have it fit correctly right out of the box, especially if it's an aftermarket installation. My wheel speed sensor is OE but not OEM as well, and it needs a little file-to-fit touch up.

0.3 mm or 0.012" is the specified distance between the tone ring & sensor.

Yeah same with mine (OE). Those things are almost impossible to get out once they are installed though without breaking them.

turbotorq · Sep 4, 2018

rshelor said:
That is something I considered, seeing as I replaced wheel bearings, but it should not have changed the gap. Any idea to what the gap spec is? Thanks to all. I would be a happy person if the machine would throw a code, otherwise its all a big guess. But until then, outside of an excessive gap between sensor and inductor ring, I must live with the intermittent problem.

My bew does the exact same thing. Don't expect a code, mine has been doing for over 70,000km and I don't have any codes. No idea what it is, I have bigger issues with my car to fix then the abs. camshaft , AC, clunking in the control arm bushings, radio and cigarette lighter both decided to stop working.

Sorry.

Just venting

compu_85 · Sep 4, 2018

Matthew_S said:
Use a scan tool to monitor all four wheel sensors. When you come to a stop one of them is probably dropping to zero at low speed. The ABS computer will see this as wheel lock up rather than a sensor malfunction and will activate the ABS rather than set a code.

This ^^^

Good news is Mk4 sensors are cheap, and not that hard to replace.

https://www.youtube.com/watch?v=6C4bFzSw_zg

-J

scurvy · Sep 4, 2018

turbotorq said:
My bew does the exact same thing. Don't expect a code, mine has been doing for over 70,000km and I don't have any codes. No idea what it is, I have bigger issues with my car to fix then the abs. camshaft , AC, clunking in the control arm bushings, radio and cigarette lighter both decided to stop working.

Sorry.

Just venting

Stop venting, start doing!

I told you what it was earlier in the thread. Read a bit, then you know what to fix.

Camshaft is a known issue with earlier BEWs, my 2006 seems to be more robust than the earlier ones (knock on wood). Fix it at your next timing belt change.
AC often does need a repair within 14 years.
Control arms as well, mine were replaced with Monroe Problem Solvers which already have the stiffer bushings installed.
Radio & cig lighter are almost certainly a fuse, check fuses 41 & 42.

BakoTDI · Sep 11, 2018

turbotorq said:
My bew does the exact same thing. No idea what it is...
Just venting

scurvy said:
Stop venting, start doing!
I told you what it was earlier in the thread. Read a bit, then you know what to fix.

I'm definitely guilty of not reading enough!! Turbotorq, you gotta take some time for sure to read all the posts even when thread is well commented on. You will find, however, answers to other issues you might have, all within the same thread! That's what I love about this forum...the resourcefulness of the many guys here that are amazing at what they do!

ABS "Farting" when stopping

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