As a matter of fact I replaced the brakes about 3 weeks ago. Do you think it is excess dust from the new pads that are messing up the sensors? I didn't think of that. If this is the case has anyone had any luck with any particular brand of pads?

 

Highly unlikely that 3 weeks of dust from any pad would cause trouble.

If you get another warning light soon, it's almost certainly something other than dirty sensors. If you get a warning light at start-up, or before the car has exceeded a few MPH, that's something other than dirty sensors.

BTW, you said that when the TRAC light came on, you thought you were stuck. Not to worry, under this condition you can drive indefinitely, albeit without the benefits of ABS and Traction Control.

Good luck.

 

While it seems unlikely that sometime is the the most obvious and the reason why I say this is because I replaced my brakes and shortly thereafter I had the same issue i cleaned them and low and behold. Not only that I have had to do it twice since replaceing those pads. I do must admit i did not go for the most expensive or originald equipment and that is part of the issue. I am replacing them now to see if that cures the problem. But the second time I cleaned them they were as dirty as the first. A sugestion in the meantime is to take your car to a car wash that offers undercarraige wash at least once a month and that will help keep them clean. Mind you this is only theory but maybe worth considering. The sensors were probably dirty before the new pads were put on and the new pads just addded to the problem. That was the case with mine. I am not a mechanic and there are people here that know a whole lot more than I do, I just used process of elimination in my case. Have fun Jagging!!! XJR100

 

Ifexsa,

As you said, definitely worth considering.

It's also possible this is going on: if you've been opening / reclosing the electrical connectors as part of the cleaning process, this activity could temporarily re-establish an iffy connection. The conection might then go open-circuit again after some time in use.

I keep coming back to the idea that a small amount of dirt on the sensors just shouldn't matter. A sensor is just a coil of wire (I'm pretty sure of this) and the magnetic field established there, modulated by the teeth on the sensor wheel as it turns, is what creates the sensor signal. The magnetic field just shouldn't care much about dirt unlike, for example, an optical sensor.

I think some problems attributed to dirty sensors have actually been in the sensor connectors and wiring, which can be temporarily fixed as a byproduct of cleaning the sensors.

Just another theory ...

 

Genius! The founder of the company I work for, GE, said that genius is 10% inspiration and 90% perspiration." And as Yogi Berra might have added, 50% dirty hands.

 

Great information. I have the problem no that's intermittent. Looks like I can handle this job easily.

 

That may actually have been my problem. I know my battery was a little low. didn't know that could cause that problem. I had been doing stuff including the top down and up when I did the resistor fix, plus radio on and doors open. Didn't know a low battery could cause this problem.

 

The are many instances where the ABS ASC light goes off after a brake job. The connectors are sensitive and moving the calipers around can disrupt the connection.

Dirty wheel sensors can definitely trigger the light. There are 3 metal strip pick ups at the bottom of the sensor and those should be shiny after cleaning them.

Also nuts and bolts on this car are metric and the correct socket size for the speed sensor bolt is 7mm.

 

Well my bad luck with my "00 xkr continues...I just completed the replacement hose and PRV install with success (thanks a million Gus!!!) only to get the abs light along with traction/asc not available warnings. I pulled the speed sensors and cleaning them up but once reinstalled the abs light remained on. The other two warnings reappeared but only for a half second. They have not come on since. Does this mean I have a different underlying problem since the abs light remained and the others disappeared??

Thank you to everyone that has contributed to this thread. It has been extremely helpful.

Regards,

 

never mind. I already mentioned it in post 67

 

So the traction control/ABS was fine before you swapped hydraulic hoses and it showed up afterwards? My first thought is a low battery. Just drive the car around for a while and it might go away the next time you start it. If that doesn't fix it, take the car to an auto parts store and have them load-test the battery (it's free). If it doesn't need a new battery, then more troubleshooting is in order.

 

When I get these messages I can take the cr to the car wash and run through it with the underbody rinse and the messages go away for days and then come back.
With this and the info you have provided I am willing to bet my sensors are dirty....
Any other related info out there??? Wonder what Jag charges to do this?

 

Sam, I'm not familiar with the design of the speed sensor. What are we cleaning with the tooth brush and soap after we take it off the car?

 

Edit: my post here was way too simplistic. Better to refer to Sam's post, immediately following.

Pretty sure the sensor is just a coil of wire inside some sort of non-ferrous metal casing.

The sensing principle is that the coil sets up a magnetic field, and there's a little toothed ferrous wheel turning with the road wheel that makes the magnetic field wiggle a bit as each tooth goes by. This makes a series of pulses that are counted to measure the speed at which the wheel is turning.

Something like that anyway ...

 

The sensors are called Hall Effect Sensors and this article on Wikipedia explains how they work. The ones on the Jag are encased in a chunk of black plastic. Once you remove it it will be pretty obvious how to clean it. Just try to keep water out of the electrical connector and scrub the rest with soap, water, and a toothbrush.

 

There is a little metal in the brake pad material and some from the rotors wearing.
I assume over time it can buildup of the sensor and change its characteristics a little and set the code.
If after cleaning the sensor the code does not return you are okay.
If after awhile it does return replace the sensor as it is no doubt has drifted out of range.

If cleaning does not change anything then:
A worn wheel bearing can cause the code too because the tone ring wobbles so the sensor sees pulses out of range.
Yes, connectors can be a problem too.

 

Wow! Thank You!! The pix's made me try it!!

 

This worked like a charm. The only thing I would add is that a metric number 8 (8mm) wrench worked better on the sensor bolts.

All the best.
Sheridan

 

UPDATE! I just added a video to the very first post in this thread. In a previous post markgr pointed out that the front sensors can be removed just by turning the wheels to the side. That's the way I did it in the video. It's much easier than removing the wheels. It took me a grand total of three minutes to remove both the left front and left rear speed sensor. Of course, I already had the rear wheel off, but with a floor jack and an impact wrench that's just a two minute job. I estimate that I could probably do all four corners in about ten minutes, and that includes jacking up the rear end, removing the rear wheels, putting the wheels on, and lowering the car.

 

And on a hoist?