Today I cleaned all 4 sensors on my XK8 wheels. I was careful to include cleaning the two little holes and blowing them dry with air. I cleared the trouble code that said "left rear sensor failure" and took a ride. At first it looked like success, no message except for my "top not latched" message. I was stoked, another thing off my list! However, it was not to be, when I pulled up to my mailbox on the way home, the message reappeared. Maybe it was because there is a little gravel on the road, and maybe the wheel slipped just a little. I don't know. I guess I will order a new sensor and see if that fixes it.
Well, I was happy for a little while.......

 

Before you spend money on a sensor, swap with the other side to see if the fault moves.

 

Somewhere here is a discussion of testing the resistance of the wiring and sensors from the ABS connector. Any issue there is what the MIL is reporting.

 

It's often the cable at fault, particularly where it can flex against a mount or tie. Here is a trouble shooting guide, but note the resistance readings are often much lower and still okay.

http://jagrepair.com/images/AutoRepa...heet%20XK8.pdf

 

Whenever you clean your wheel speed sensors, be sure to clean their electrical connectors at the same time. Cheap, easy, quick, and it may solve your pesky problem....

As others have said, have a good look at the cables as well. They pull and chafe and split. My wife's XK8 has splits in the cable rubber boots on both of her rear wheel speed sensor cables. At the 60,000-mile service I'll do in a couple of weeks, I plan to remove the electrical tape I covered the split boots with a month or so ago, clean the boots thoroughly, and fill the splits with some flexible silicone caulk I bought exclusively for this purpose. The car is not throwing any wheel speed sensors warnings currently, but if I do not address this split boot problem on a more permanent basis than the current electrical tape fix, I feel certain it will begin throwing warnings again once the tape's adhesive begins to release and allow moisture/grime/whatever inside the cable sheath again....

 

Thank you for the helpful replies. I did find that the rear rubber boots were toast. I checked the wires, they seemed OK. So I carefully wrapped them both in "self effusing tape",something I was not aware of before. This type of tape has no detectable adhesive, but as you wrap it around itself it seems to mold itself together. After a few minutes it looked like a solid sheath of rubber.
I intend to measure the resistance at the ABS plug tomorrow. Then I might try switching sides as was suggested.
Thanks to all for your help.

 

Well, this morning I continued my quest to solve my "ABS Not Available" error message on my XK8. I disconnected the main ABS plug and used the excellent guide at http://jagrepair.com/images/AutoRepa...heet%20XK8.pdf
The guide says to expect around 2K ohms. My readings are almost exactly 1K ohm, but they are all consistant. Hardly an ohm difference between them. So I think that rules out the sensors themselves and probably the harness,unless it is intermittent. Maybe I will try to check out the module next. I will report if I find anything useful.

 

I don't recall anyone reporting 2K ohms in the past year or so, all 1K-1.5K. I just put my ABS module back in after sending it out for repair and I still get Left front sensor error. I have checked the cables and sensors and swapped them with no change.
Maybe I'll just have to get used to the ABS/ traction control not available.

 

Thanks for the information RJ237. I hae resigned myself to living with the "top not latched" message. It would hurt my pride to have to live with the ABS message too. So far it is still an interesting challenge, but I hope I don't come to the point where I start to believe all the "Jaguar,s are nothing but trouble" point. My wife is already asking me if I am sure this is the car I want. The answer is yes.......at this point.
As far as I can tell, the brakes work fine in spite of the error message. We are planning a trip to the coast next week, in the Jag. I have my fingers crossed.

 

I cannot stand it when any of our vehicles displays a fault on the dash, actual or spurious. It bothers the hell out of me, causes my wife to be apprehensive about driving it, and really hammers our ability to sell the vehicle if we suddenly decide to do so. That's one reason why I just have not been able to warm up to my wife's XK8 although she's had it for 13 months and nearly 24,000 miles now . The quirky and far-too-complex electronics continue to concern me....

 

Too early to do the victory dance, but I may have fixed my ABS problem. The scanner again told me that the left rear sensor was bad. So once again I probed the connections at the ABS controller and again it showed all was well at about 1Kohm. All four showed the same reading. So I decided to go a little further and hook up my oscilloscope to see the actual wave forms. I started with the front left wheel because it was handy. I found a nice sine wave with about 10 volts peak to peak when I spun the tire . Then I probed the left rear wheel, the one that the ECU said was faulty. The wave form looked just fine. I was about to give up, but something led me to remove the rear wheel and start the engine and let it turn the rotor. Then as it was turning I carefully manipulated the wire. Sure enough at some point the signal stopped. There was a broken wire that would make intermittent contact. Hence the good reading with the voltmeter in a static condition, but intermittent in actual operation. The bad news is that the wire was broken about 1/4" from the connector, leaving very little room for a repair. But I did manage to solder them together and they seem to be working. I drove the car for about 10 miles and so far no error message. We will see what happens this weekend on our trip to the coast. And I need to find a donor car with a connector with a little more lead to do a proper repair. have my fingers crossed......

 

I'll bet you've cracked it.
Waggling the wires or, for a front wheel sensor, going lock to lock while measuring resistance can show up an elusive break like that.
Let us know.

 

Best I can remember, this is new information for us. Not just about your car, but generally. I recall cases of broken wiring on front wheels and that sort of made sense given all the flexing that goes on up there. But this tells us to put another possibility in play (like we didn't have enough already, right?)

Nice detective work.

 

It's not just the front wheel speed sensors susceptible to these wiring harness problems. Again, everyone should check your rear wiring harness rubber boots as well. Chances are they're split open, meaning the two wires inside them are vulnerable to the elements and may be chaffed through their sheaths. I have both of my wife's XK8's rear rubber boots taped up at their splits with electrical tape right now, but when I do the 60,000-mile service on the car in the next couple of weeks I'm going to permanently seal up the splits with flexible silicone caulk....

It's a good idea to check the cleanliness of your wheel speed sensors and the condition of their wiring harnesses whenever you do a tire rotation, or any other time you have the wheels off the car....

 

Lanny, good to hear your problem is resolved. Mine is also. The ABS light went out today with no further action on my part after sending the module out for repair. It took a couple of drive cycles, but now the c1155 code is gone.

 

Well, we have traveled 200 miles from my home to the west coast, Fort Bragg. At the 60 mile mark the "abs not available" message came back. Then we stopped for lunch and after restarting the car the message was gone. It has not come back yet, but this is another day. We hope to cruise up and down the coast hyway today. Lots off turns and bumps. We will see. I suspect I still have a ghost in the machine.

 

Maybe more than one bad harness - not impossible.

 

Try pulling and reseating the ABS wires at the pump- can't hurt.