Full Frontal wheel speed sensor removal

BBB · **Posted:** Wed Jul 15, 2009 8:29 pm

Saw a post awhile back that stated the wheel speed sensors can get dirty or fail and cause the ABS brakes to act up. I removed the rotor with Kroil and a slide hammer to gain access to the speed sensor and removed the allen head screw that holds it to the steering knuckle/hub but it doesn't want to come out. I tried gently prying upwards on the plastic piece and it started cracking :shock:

Is this speed sensor supposed to pop out after removing the allen head screw or if it's rusted in the hole will it shatter and need replaced? How about rotating it gently? (She likes that) I've never had one out so I just want to be careful...thanks.

warp2diesel · **Posted:** Wed Jul 15, 2009 9:53 pm

Best of luck getting the speed sensor out in one piece.

BBB · **Posted:** Wed Jul 15, 2009 10:06 pm

So it turned into a press/ friction fit after it left the factory and encountered moisture mixed with salt. :roll:

I see... Then do you drill it out after it desintergrates and if so what size drill do you suggest? Do the pieces fall into the hub or just drop out the bottom? It got dark so I just put everything back together for now.

warp2diesel · **Posted:** Wed Jul 15, 2009 10:14 pm

BBB wrote:

So it turned into a press/ friction fit after it left the factory and encountered moisture mixed with salt. :roll:

I see... Then do you drill it out after it desintergrates and if so what size drill do you suggest? Do the pieces fall into the hub or just drop out the bottom? It got dark so I just put everthing back together for now.

I have had to smash them to pieces to get them out before when they are stuck, I would not attempt to drill it out. Chip out the rust from the inside of the hole with a drift punch until you can slide it in gently, then follow up with anti seize in the hole before you reassemble the new one.
Bean Counters will not allow anti seize to be used, cuts into the bottom line too much.

Know where I can buy or download Bean Counter Targets?

gmctd · **Posted:** Thu Jul 16, 2009 12:17 am

I use a drywall screw long enuff so a set of dikes fit between the head and the knuckle, then pry - repeat as necessary - if need be, drill smaller than the screw diameter - the coarse threads bite deeply into the plastic and the offending bit comes out - clean the rusty\dirty bore with a rifle brush, lube the new sensor, insert and yer good to go................

bbertram · **Joined:** Mon Dec 19, 2005 4:17 pm **Posts:** 144

I'm thinking I may need to replace or clean my front speed sensors. When I go over 80 kph my emergency brake and ABS light ding on and my odometer stops. I fixed my rear speed sensor, it had a broken wire. Before I fixed that my odometer never worked!

warp2diesel · **Posted:** Thu Jul 16, 2009 10:26 am

bbertram wrote:

I'm thinking I may need to replace or clean my front speed sensors. When I go over 80 kph my emergency brake and ABS light ding on and my odometer stops. I fixed my rear speed sensor, it had a broken wire. Before I fixed that my odometer never worked!

You may get lucky and only need to clean off rust on the trigger wheel.
I have replaced them on various cars over the years including two on my Wife's TDI, both on the left side front and rear. They are nothing but a coil of very fine wire wrapped around a core, the pulses are sent to the controller and it does its' various jobs. As the rust builds up in the spindle hole it puts more and more pressure on the plastic until it distorts or destroys the coil and it quits working. Corrosion at the plug will cause a weakening of the signal and the controller will not see the signal and start causing problems.

For other parts of the country or world where they don't put on rock salt like road gravel in the winter, lubricant in the bore may work.
For the Salt/Rust Belt or other spots on the planet that have corrosion problems, anti seize is the best choice.

BBB · **Posted:** Thu Jul 16, 2009 12:51 pm

First we would get an occasional ABS light when driving thru heavy rain so I checked all of the speed sensor splice connectors and re-seated the main ABS controller connector. We still got the ABS light and finally it started deploying the ABS pump whenever we braked so I pulled the ABS pump fuse. The vehicle brakes normally albeit without ABS. Now, of coarse, the ABS light constantly stays on and the Brake warning light comes on and goes out at random.

We threw a 1256 code awhile back that will not go away and when I went to the dealer they said they couldn't find that code listed anywhere but said they think it has something to do with a brake peddle position sensor if there is such a thing. Unsure why they said that's what they think if they couldn't find the code listed unless it was close to a group of codes

warp2diesel · **Posted:** Thu Jul 16, 2009 9:30 pm

BBB wrote:

First we would get an occasional ABS light when driving thru heavy rain so I checked all of the speed sensor splice connectors and re-seated the main ABS controller connector. We still got the ABS light and finally it started deploying the ABS pump whenever we braked so I pulled the ABS pump fuse. The vehicle brakes normally albeit without ABS. Now, of coarse, the ABS light constantly stays on and the Brake warning light comes on and goes out at random.

We threw a 1256 code awhile back that will not go away and when I went to the dealer they said they couldn't find that code listed anywhere but said they think it has something to do with a brake peddle position sensor if there is such a thing. Unsure why they said that's what they think if they couldn't find the code listed unless it was close to a group of codes

There should be a link in the CRD tech section, Sir sam knows where it is if you can't find it after looking.

Full Frontal wheel speed sensor removal

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