Trac not Available message on my 2003 X308 XJR

[AJL]

Hi, all;

"Trac not Available" has started appearing in the message centre on the first start of the day. No lights or other messages are appearing, i.e., no ASC light or message. Happens in cool weather and in very hot weather.

The battery is two years old, and there have been no events to flatten it. The alternator was rebuilt about ten years ago. After a few hiccups after that work through the dealer -- I would get a "battery not charging" message -- I believe they had to add another rectifier (?), and all was well. Memory fails, but I think, in the end, they felt that the alternator for the XJR was different than for the XJ8, and they'd put in the incorrect one. I could be wrong; as I say, memory fails. But that additional rectifier solved the problem; the "battery not charging" message was never seen again.

I hooked up my iCarSoft930; no faults were registered, there were no codes to clear. I placed it in diagnostic mode, navigated to the ABS subject area, and my wife drove us around at a speed of about 35-40 km/h while I recorded the active data from the speed sensors generated on the iCarSoft.

Right front was 0 km/h.

Left front was in line with the posted speed we were driving at 33 km/h.

The two rear speed sensors registered a very impressive 146.5 km/h, which meant the rear of the car arrived home first:)

That the two rears were recording the same, albeit high, speed didn't bother me as much as the right front sensor reading zero km/h; so I turned the wheels full lock and swapped it out with a spare. Another road test, and all numbers were essentially the same, with the right front still reading 0 km/h.

I started the car this morning, and there it was again, a brief flashing of the "Trac not Available" message.

I've looked at other threads, and battery is often pointed to as an issue, as are failed soldered joint on the ABS Control Module -- if the ASC light and message are also in play. I've had the ASC light before -- about fiver years ago -- and that was after driving down a very dusty road. Turning off the car, and then restarting the car resolved it. And upon returning home, I removed and cleaned all four ABS sensors; that ASC message and light have not been seen since.

I'd very much appreciate it if anyone has had success in resolving this issue, or can point me in the right direction.

Kind regards,

Adam

[andypryce]

With the right front showing 0km/h you would suspect the sensor, I am unsure if the OBD2 system was advanced enough in 2003 to show a fault code for each ABS sensor, others may know. I know on my 98 XK8 it doesnt and on my 2006 XK it did. May be worth swapping sensors round and retry, it's a fairly simple task at least.

[AJL]

Thanks, Andy;

Ah, Liverpool. My dad was a Brit and we visited from Toronto in 1969; one of our excursions took us to Liverpool. I would have just turned six, but I remember the big beach, and digging a deep hole, getting in and peeking out. Later, along walked a group of school boys in their uniforms, and one fell in. One minute he was there, and then he wasn't; I couldn't believe my eyes. An unintended consequence. They all laughed themselves silly, and I remember them talking to us about our visit; just one of those nice moments you remember. As they walked away, my Dad said that perhaps it might be a good idea to fill the hole in? And I did.

Years later, parents long gone, I finally went into the box of home movies of the time and the trip and had them converted to digital. A great colour movie of my older sister, happy -- joyous, really -- having a donkey ride with other kids and a fellow looking a bit worse for wear, running along riding herd.

Those are my Liverpool memories; good ones.


You may well be right; while the iCarSoft 930 does appear to allow you to select under Diagnose (as opposed to selecting "OBDll Diagnose") each wheel and get real time data (and to select other sensors for real-time data), it may not be able to populate the fields, or do so correctly.

There was another posting some time ago from another member whose measurements seemed very similar to mine, i.e., one very close to the speed being driven, two equally well out of range, and the same wheel at zero, but his issue seemed to come with the ASC light, although I may be wrong.

But I agree with your suggestion, I'll remove the other three, clean them, and move them about and see if the readings change, or stay the same. I have a few spare sensors from wrecks, so I can sub in a few of those too -- aware that they may well have failed.

Adam