XJR100 Cant Find Traction control

[Jeggers]

Hi Guys

Have just had my car serviced and work carried out from a cautionary note from a recent MOT All £861.99 worth. Hey Hum

During the service I asked for codes to be checked on the ECU as I have had warnings on a couple of occasions that the traction control could not be found but on restarting the car a couple of times it would go away. Just to point out the car only gets used at the weekend and if its going to happen it will be on starting the car after not being in use for 5 days, maybe 6.

Well the other day after Jaguar said they had cleared all codes from the ECU and just to keep an eye on it, the car on crawling through traffic shuddered to a stop saying it could not find traction control and knocked it self in neutral and flashed up limp home mode for a second. After switching off and restarting all was fine again, but am fearful this could be expensive one.

The previous owner some 15 months ago had the ECU replaced at a cost of £1100 after having engine warning lights flash up different things.

Sorry for the long windedness but does anyone have any ideas apart from trickle charging the battery over night?

Regards

Jeremy

[P700DEE]

Poor connections or a damaged cable on the ABS sensors. Do not get fobbed off with the ECU fault and replace as quite often the fix lasts a few weeeks where they remade the connection then returns. Check all the sensors and cables with a multi tester and pull them about a bit to see if you can see a fault.

[Cecil]

Check the earth to the body for corrosion also

[Tame Technician]

If it only happens when starting from cold, then its just battery voltage drop out. ABS ECU (which does the traction control) will switch off if the battery voltage drops bellow say 10 volts. IT will drop bellow 10 volts when cranking from cold with a partially discharge battery.

If while driving it goes into limp-home and displays the fault then it sounds like a CAN BUSS fault, possible a connection at the ABS ECU, but could be anywhere on the buss.

[TurricanII]

Lots of posts on here about the low battery causing traction control and ABS errors etc. - defo worth a new battery at £70 to £100 to see if it clears up. After a while of weekend only use my original battery was screwed even after removing from the car for a full day of charging from a ctek conditioning battery charger. Been fine for months now after a new battery. As posted on an earlier post I would recommend a ctek charger for future use. I reverse up to my garden shed, pop the boot and plug the car in to charge using the included easy connector plugs.

[Jeggers]

Thank you all for your comments so far. Have got the car booked in Thursday to get codes read and some sort of advice on way forward and cost.

Tame Technician, all prior incidents have been from cold apart from the last time which went into limp home mode while driving some 10 mins into a journey. You say this could be a CANN BUSS fault maybe at the ABS ECU. Any idea of a ball park figure? And do you reckon they will charge for reading the codes to get a quote for work to be done?

Thanks again ALL

Jeremy

[Tame Technician]

Jeggers said:

all prior incidents have been from cold apart from the last time which went into limp home mode while driving some 10 mins into a journey.

Sounds like a different fault to me. First you need to know, Is it a good battery?

Are the connections at the battery good and free from corrosion and the same for the connection between the battery and the body shell.


The worry is, you wouldn't normally get limp mode with any ABS fault, wheel speed sensors, pressure sensors switches etc would just put the ABS and trac warnings up, the car would drive normally just with no ABS/trac functionality. Thats what makes me think its a fault on the CAN network. Maybe if the transmission or engine ECU's cant see vehicle speed (which the ABS ECU is supposed to broadcast on the CAN network), it might go into limp home

The jag dealer I used to work at would charge 0.3 hrs to read the fault memory, but if we'd cleared them and said take it for a bit and see what comes back, we would re-read them for free.

I'm sorry but I doubt it will be very straight forward to diagnose if it does turn out to be a CAN fault, cant recall without going through the diagram exactly how the network architecture is, but Engine ECU, Transmission ECU, ABS ECU and Airbag ECU are all on that network so could be a fault with any of those modules or the wiring in-between. To diagnose that wouldn't be a case of just reading the fault memory.

But lets not get to much doom and gloom until you have the fault memory read again and see whats in there.

Regardless of the outcome Ask them to print out the fault memory so you can post it up here.

[Jeggers]

Tame Technician. Just to let you know that i now have the car booked in for Monday for the codes to be read, so will post on here tuesday.

Will look at all you have advised so far over the weekend as in battery and earths etc

Regards

Jeremy

[Jeggers]

Guys

Turned out a cell was shot on the battery. New Jag one fitted so hopefully this will sort.

Thanks again

Jeremy