Trac light

[teknimart409]

Hi Brian

Thanks for your suggestions
I checked the car this morning having previously cleared the codes and now the car runs OK with no codes present, (I ordered an new coil just in case.)
I checked the wheel sensors which gave the following
Fr left 36.83kph
Fr right 0kph
Re left 146.25kph
re right 146.25kph
I haven't a clue what this means, I have recently checked each sensor with a meter whilst rotating each wheel and they seemed OK
Any ideas? Something else I have just noticed is the ABS light comes on briefly after stating the car and Trac not available also flashes up but there are no codes.

Regards
Martin

[BrianG]

Hi Martin,
Glad you have cleared the codes this morning, and pleased you navigated the iCarSoft menus to get to the wheel speed sensor section. However, the front right wheel speed sensor reading 0kph is definitely wrong if the others were giving valid readings. I don't know exactly how you went about checking these but an assistant to view the readout, or someone else driving is the safest bet while reading such data on the move. I would re-check that all four speed sensors agree within a gnats of each other when you are driving at a steady speed, e.g. 20 mph will do. If they disagree by more than a little (allowing for different tyre wear etc.) then traction control or stability control will start to cut in. If front right wheel persists in reading zero then that is the answer to your Trac light problem and the sensor circuit needs further investigation.

I assume the wheel sensor on the X308 uses an inductive sensor (it has a coil) if you can test them with a meter on the car. (This does not work with the X350 as they are Hall-effect sensors) As you say you get a similar reading when spinning each wheel it suggests that the slotted ring the sensor aligns with on the wheel is OK (the fault here can be the slots can fill up with rust; the ring can be broken by expansion of the rust) If the iCarSoft readout still insists the reading for the right front wheel is zero on a road test then that means there is a wiring fault on the way to the traction control module, or a fault in the module itself.

Regarding the brief ABS and Trac message when/just after starting the car, I remember mine used to do this sometimes, especially in winter when cranking takes more toll on the battery voltage. How old is your battery? (month/year four digit code is stamped on one of the battery terminals) As it sets no codes you can probably ignore it; think about replacing the battery if it's over 7 years old.

Regards,
Brian

[teknimart409]

Hi Brian
Thanks for this, I will test the wheel sensors on the move this morning, I will let you know.
By the way, the battery is new as are the plugs. The car has gone in to limp mode several times the first time came up as a coil issue. Now last time I read the codes all was clear doesn't make sense

Cheers
Martin

[teknimart409]

Hi Brian

I am beginning to suspect the i930 scanner isn't working properly. In OBD11 mode it won't talk to the can and whilst moving the wheel sensor say the same reading as when stationary (the same figures I sent you)
I have looked on the web and a few people say there is a comms problem with some jag ECU's and the i930
Any thoughts?

Martin

[BrianG]

Martin,
It may be possible that your year car (what is it?) may not be covered or have comms problems, but first I think you may not be using your i930 correctly. This would not be surprising since the documentation is bloody awful, the buttons keys are very limited and can have more than one meaning. The correct menu to use for live data is DIAGNOSE, not OBDII. The menu layers and choices you need to go through should be as follows (-> means press this key next):

Diagnose -> OK
Jaguar -> OK
XJ -> OK
Year [select your year]-> OK
Normally Aspirated V8 -> OK
Manual Select -> OK
ABS Control Module -> OK
Read Data -> OK , then press down arrow 3 times to go down the pages to get to speed sensors page:

Front Left wheel -> OK. Then [-] symbol on left changes to [V]. Now press ESC to see actual live data readout in kM/h.

Press ESC to go back up one level to select next speed sensor in list, then as before:

Front Right wheel -> OK then [-] changes to [V] then press ESC to see actual data in kM/h. etc. etc. Press down arrow to get further pages.

Press ESC to back up one menu level each time or select different area of interest.

All being well you can see what the real data is on the move from all four sensors.

Regards,

[teknimart409]

Hi Brian

That's what I have done, I have just tried it again through the procedure you have written and it is the same, the reader is not registering movement at the wheels. Whilst I was out, it went in to limited performance mode so I went through the dtc's and nothing was recorded which also doesn't make sense. The only thing I can think is that the reader has a problem (purchased 2nd hand off ebay!)
I have access to my old s type so I am going to test on that but to be honest, I am losing the will. It is a lovely looking car (2000 plate)
and I have checked this car is OBD11 compliant but I have had lots of cars including 3 jags and they are by far the least reliable given of course they were all quite old. Just for the record I have had 2 Toyota's all I did was put petrol in them!
Once again thanks for your help Brian

Regards
Martin