# Weird ABS problem



## manoweb (Jan 27, 2014)

Hello. I replaced the CV axles and the front wheel spindles/hubs as the old ones were totally seized together. Now I have an ABS light and the VAG-COM shows the code as "Intermittent Front Left". I removed the wheel, cleaned around the sensor, cleaned the contacts, the ABS wheel speed seems to be in order, the resistance on the sensor is just above 1k (so it should be fully within spec) and tested again with VAG-COM. I was able to get into the "measurement blocks" and I saw the speed increase as I turn the rotor with my hands.

I remount the wheel, go for a test drive, it seems to work OK.

Next day, even before I have a chance to move the car, the ABS light is already on. I drive around with a laptop connected with VAG-COM and sure enough, I get very werid readings from the front wheel tire; sometimes the same speed as others, sometimes half of it, sometimes zero.

What do you suggest to do? Should I just get new sensors and try?

Thank you


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## manoweb (Jan 27, 2014)

This is the actual output with the fault codes as I read them again this morning:

Control Module Part Number: 1J0 907 379 G
Component and/or Version: ABS 20 IE CAN 0001
Software Coding: 03504
Work Shop Code: WSC 00066
2 Faults Found:
00283 - Front Left ABS Wheel Speed Sensor (G47)
35-10 - - - Intermittent
00283 - Front Left ABS Wheel Speed Sensor (G47)
04-10 - Mechanical Malfunction - Intermittent


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## tongsli (Jan 21, 2002)

Did you try Deoxit spray on the connector and adding anti-oxidant paste? The sensors are cheap $25 but a PITA to get out. If you measured the resistance and they check out ok try the spray.


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## manoweb (Jan 27, 2014)

I have used flux clean, the contacts are very clean, gold plated.

I might have to add that I think that wheel hub is vibrating, or at least is making some noise that varies with speed of the car. Is it possible that the bearings need to be changed and that has an impact on the ABS? I read something like that in the past, but I cannot find it again now. Also, in any gear, at about 3.5krpm I feel a vibration that disappears when I go above 4krpm. I am reporting this because it might be relevant, I don't know. I had alignment done very recently, new tires, new front struts and ball joints...


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## tongsli (Jan 21, 2002)

manoweb said:


> I have used flux clean, the contacts are very clean, gold plated.
> 
> I might have to add that I think that wheel hub is vibrating, or at least is making some noise that varies with speed of the car. Is it possible that the bearings need to be changed and that has an impact on the ABS? I read something like that in the past, but I cannot find it again now. Also, in any gear, at about 3.5krpm I feel a vibration that disappears when I go above 4krpm. I am reporting this because it might be relevant, I don't know. I had alignment done very recently, new tires, new front struts and ball joints...


The tolerance of the ABS sensor is 2mm to the ring so yes, a bad wheel bearing will cause problems and is most likely the problem. If your bearing is bad then that is more of an issue right now than the ABS light


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## manoweb (Jan 27, 2014)

Interesting. Other that this "vibration noise" how can I assess the status of the wheel bearing? I don't mind putting new bearings (I will do both sides at that point) but at least I would like to be sure they are bad before I proceed 
I should have done this before the suspension job and alignment...


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## tongsli (Jan 21, 2002)

*Wheel bearing*



manoweb said:


> Interesting. Other that this "vibration noise" how can I assess the status of the wheel bearing? I don't mind putting new bearings (I will do both sides at that point) but at least I would like to be sure they are bad before I proceed
> I should have done this before the suspension job and alignment...


Well, 

You can try jacking up the car and hold the wheel and try to move it back and forth, side to side. If it moves, it could be a tie rod end, ball joint or wheel bearing. If you keep driving it will get worse and worse. If it gets bad enough, your brake pads will rub when you turn to the opposite side of the bad wheel bearing. (don't ask me how I know this)

can you tell the difference between a wheel bearing and badly worn tires? Sometimes they can sound very similar.


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## manoweb (Jan 27, 2014)

Well the tie rods are brand new and I also got brand new tires few two thousand miles ago... so no, I do not expect to be those. I will anyway rotate the tires soon so I can see if the noise appears to change the direction it comes from...


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## racerpoet (Apr 20, 2013)

manoweb said:


> I have used flux clean, the contacts are very clean, gold plated.
> 
> I might have to add that I think that wheel hub is vibrating, or at least is making some noise that varies with speed of the car. Is it possible that the bearings need to be changed and that has an impact on the ABS? I read something like that in the past, but I cannot find it again now. Also, in any gear, at about 3.5krpm I feel a vibration that disappears when I go above 4krpm. I am reporting this because it might be relevant, I don't know. I had alignment done very recently, new tires, new front struts and ball joints...


Sounds like you know what you're doing but I'm a little confused, so I'm trying to clear this up.  If the spindles were rusted onto the CVs, how did you get the CV out? Did you support the back side of the wheel bearing when you pressed in the spindle/hub? Just asking some obvious questions to get them out of the way. Also, when you put in the CV axles, did you torque the nut/bolt? Did the wheel bearing hum/noise start after or before you did the work?

And agreed with tongsli, if the WB is loose that's the first thing you should address. Pulling the sensor is cake in comparison.


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## manoweb (Jan 27, 2014)

racerpoet - I removed the cv axles, the steering knuckle/spindle/wheel hub and the strut as a solid unit as it was all rusted together. I put brand new (aftermarket, non original) CV axles, new struts, and I got two used" knuckles from ebay. I could not reuse the old parts.

Apparently, the driver side steering knuckle I got had a broken wheel bearing


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## KG18t (Aug 9, 2006)

I had a shop put one of the ABS sensors in at the wrong angle once - gave readings like you're talking about (a second improbable but possible retaining screw location). Make sure the magnets are on the same axis as the vanes on the ring.


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## manoweb (Jan 27, 2014)

Interesting, I will check again, but I am pretty sure the sensor is installed correctly.


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## KG18t (Aug 9, 2006)

manoweb said:


> Interesting, I will check again, but I am pretty sure the sensor is installed correctly.


That, and/or make sure the gap between sensor and ring is the same all around.


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## racerpoet (Apr 20, 2013)

manoweb said:


> racerpoet - I removed the cv axles, the steering knuckle/spindle/wheel hub and the strut as a solid unit as it was all rusted together. I put brand new (aftermarket, non original) CV axles, new struts, and I got two used" knuckles from ebay. I could not reuse the old parts.
> 
> Apparently, the driver side steering knuckle I got had a broken wheel bearing


Did you get a chance to have the bearing replaced. Again, that's the first thing I would do. Then clear the ABS module. If the code comes back, change the sensor and forget about it. After the bearing is replaced see if you can watch all four wheel speeds on your scanner while driving/braking. If the left front is sporadic (once in a while) or goes to zero before the others when you're stopping, just change the sensor. By any change can you pull out your old sensor from your original knuckle?


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