# ABS Light Still On



## jharmon718 (Sep 5, 2008)

Last week I replaced my LF wheel bearing and after that was all done I put it back together and when I went to start my car my ABS light was on. I had a guy at my job scan my car and it said something along the lines of LF wheel speed sensor fault. So I replaced the sensor thinking I messed it up when I removed it. And I disconnected my battery for about 20 min to reset the light on my dash and it came right back on. What other problems would cause that problem but say the sensor.is bad.

Sent from my DROIDX


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## JayJetta (Mar 29, 2001)

Did you scan it after you replaced the sensor? We sould really need to see what codes she's throwing... 

I have/had a similar problem where my EPS light stays on and through my research i discovered the ABS units tend to fail. I swapped out the brake light switch for the newer purple one (mk iv) and i've been alright for 2 days.


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## GTijoejoe (Oct 6, 2001)

More than likely, the airgap for the sensor head is too large.. meaning the bearing isn't fully seated is going to be my assumption and/or (depending on the construction) the encoder ring isn't installed properly. 
I don't think this is a coincidence with a LF wheel bearing install and a LF abs sensor fault code imediately after :thumbup:


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## supermega1 (Oct 27, 2006)

Check to make sure there is no debris on the sensor itself (its a magnet) also make sure your abs speed sensor ring isn't missing any spokes.


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## KG18t (Aug 9, 2006)

The ring that the sensor reads off of should be at max 3mm away from the sensor head, and never touching it directly. If you can find someone with a VAGCOM you can get a real-time reading of the sensor output.


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## GTijoejoe (Oct 6, 2001)

KG18t said:


> The ring that the sensor reads off of should be at max 3mm away from the sensor head, and never touching it directly. If you can find someone with a VAGCOM you can get a real-time reading of the sensor output.


 No offense but this is not accurate in anyway shape or form... all sensors can have a different reading max airgaps, it depends on the encoder's strength, the specific chip it self that is used in the sensor head, and the given voltage the sensor uses to detect what the sensor airgap can read. 

Majority of 'active' type sensors can not read 3mm away.... older 'passive' type sensors could read slightly more because of the magnets in the head. 

..just FYI :thumbup:


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## carlosabh (Jan 21, 2003)

On ABS modules, you have to clear the DTC's with a scan tool (VAGCOM, VCDS) those won't clear disconnecting the battery by themselves, when you reconnect it again it will turn on the ABS checklight again.


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## jharmon718 (Sep 5, 2008)

This problem is fixed. It was a broken wire at the base of the connector to the abs sensor. I replaced the connector and a few inches of wire... drove the car and the light went out.

Sent from my DROIDX


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## killian86 (Apr 6, 2021)

jharmon718 said:


> Last week I replaced my LF wheel bearing and after that was all done I put it back together and when I went to start my car my ABS light was on. I had a guy at my job scan my car and it said something along the lines of LF wheel speed sensor fault. So I replaced the sensor thinking I messed it up when I removed it. And I disconnected my battery for about 20 min to reset the light on my dash and it came right back on. What other problems would cause that problem but say the sensor.is bad.
> 
> Sent from my DROIDX


mine now is the same I changed the sensor and ring and still on


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