I recently replaced the front wheel bearings on my 2004 X-Type. I then began having ABS issues where the ABS pulses constantly under braking after the vehicle is first started. The system faults out after about a mile and the ABS light comes on. I used my code reader to check the wheel speed signals from all four wheels. The two front wheel speed signals are exactly 50% of the rear wheel speeds. I installed new speed sensors all around and the readings remained the same.

Has anyone experienced this with new wheel bearings? I thought that if they were installed backwards, then there would be no speed signal from the fronts, but mine are exactly half that of the rears.I installed National 510099 bearings which claim to have "magnetic encoders on both sides of the bearing to eliminate installation error" so they supposedly cannot be installed backwards. I have also checked the connection to the ABS module but all the pins appear to be clean. Any other thoughts?

 

It would appear to me that( the bearing that is installed has the wrong number of teeth on the ring. This would cause the speed to be wrong. In this case it has half the teeth, therefore reads half the speed. Barring a re-wire of the system, that is about all that I can come up with.

 

Thanks Chris. There are no teeth or ring on a front wheel bearing, just a flat surface that has the magnetic pulses embedded (see pic). I find it very odd that both new bearings are producing exactly half the pulses they should vs the vehicle speed, but this certainly appears to be what is happening.

 

What Chris (Thermo) wrote made total sense to me, while I already wondered, if there are actual "teeth" on the bearing, but I already figured that if that theory is correct that we are dealing with "invisible" teeth, i.e. little magnets inside of the bearing - and in this case the wrong number of them (i.e. half as many).
And now you are confirming this - that the magnetic pulses are coming from the bearing. Interesting.
Did you search for the correct part-number for those bearings before ordering them?
Are those bearing meant to be used in the X-Type, and for that model-year and type?

 

Yes, I ordered the correct parts from RockAuto. The listing for the National 510099 Bearing shows a cross reference to the correct Jaguar interchange part number of C2S8276 for the 2004 X-Type (National 510099). And there are five other bearing brands on RockAuto that also carry the 510099 part number so it must be correct. As I indicated, the National bearing also "contains magnetic encoders on both sides of the bearing to eliminate installation error," so it cannot be installed backwards. That's what has me baffled.

All I can figure at this point is that I am going to have to tear the whole front suspension apart again, cut these new bearings off and try a different brand. Just wanted to know if anyone else had experienced this issue.

 

The correct number of pulses per each revolution of each wheel is 32. How many have you got?

 

I don't know how to go about counting pulses. My iCarsoft Data Scanner gives me the actual wheel speed signal from each wheel when driving, which is how I know the fronts are half that of the rears which do match the vehicle speed.

 

autorx1, the only way that I could see doing it is to get another bearing and then using some iron filings, lay the bearing down on a flat plate and then sprinkle the iron filings down the side of the bearing. Where the magnets are, the filings will gather. This should allow you to count the magnets.