XKR Convertible Will Not Start. CAN BUS Issues

[DJB72]

Hi. Any help greatly appreciated. I have 2008 XKR Convertible that suffers with an intermittent electrical problem where it refuses to start. The dash displays various faults such as ABS, Parking Brake,Battery Not Being Charged as well as 27 other messages. Diagnostics show 16 modules with faults and 2 modules not responding. When the car is running there are no issues with how it drives whatsoever. Diagnostics also shows it has lost communication with several modules/sensors when failing to start. The fault only occurs when the engine is left to cool for 4 or 5 hours or more. The car is driven most days.
I have replaced the battery and gear selector. Also tested the battery when on the car with the engine off and it shows around 12.8 volts, with engine running it shows around 14 volts. I’ve been advised it will need CAN BUS testing and fault finding to locate the fault. Seems there’s a faulty connection or component somewhere……Any ideas on where to start looking. Any pointers will be great appreciated.Thanks

[andypryce]

First simple check is all earthing points, there are several, I am sure there is a diagram of them on another post, if I find it will forward. Bad earth would certainly cause those multiple errors.

[DJB72]

Thanks Andy. I think I have a diagram. I’ll post again once I’ve checked the earthing points. Cheers

[DJB72]

I had the earthing points checked and the earthing points in the offside front wheel arch were severely corroded.Had them replaced and it seems to have done the trick. Thanks again Andy

[andypryce]

Good result, hopefully a summer of trouble free motoring ahead!

[DJB72]

Problems Persist……I’ve had pretty much all of the earthing points checked and replaced as necessary…..Two earthing points were corroded. However, the same problem persists. The earthing points behind the instrument panel and other less accessible areas are yet to be checked.
Before I authorise this exploratory and expensive work to check these points, are there any other components I should check, eg. relays or modules? If so, which ones tend to fail? The battery and alternator have both been checked and are working correctly. The battery is new. The car is driven most days, so not subject to battery drain.
Any pointers would greatly appreciated. Thanks

[JimMann]

You don't at any point say if the car turns over and doesn't start, or whether the car simply clicks, with no engine movement.

Jim M

[ptjs1]

DJB72,

If it's not battery, this still seems like an earth problem. It's really important you check all the earth points, particularly the major body earth strap to the gearbox, accessible from underneath.

Good luck

Paul

[DJB72]

Thanks for your replies.
The car does not turn over and there are no clicking noises. There is bleeping as the numerous faults are displayed on the dash. I have already replaced the earth strap attached to the gearbox on the underside as it was corroded along with earth in the offside wheel arch. I have checked the earth points under the rear seat, in the boot, near side front wheel arch and relay clusters.
I shall continue to check all of the remaining earth points.Thanks again.

[mike020150]

Any fault which causes low voltages in the system will illuminate lots of warning lamps and error messages. An intermittent failure to start could simply be caused by a faulty starter motor drawing a high current and reducing system voltages. Consequently, it would be as well to test the starter, if only to eliminate it from the many possibilities. Disconnecting the starter from the wiring loom and running a 12v source direct to it would confirm if it's working. Needless to say, since the failure only occurs when it's fully hot, the test would have to completed during one of its usual failure periods, not when the engine's cold. Mike.

[andypryce]

In addition, it is unlikely to be internal earthing points as obviously they are not exposed to the elements so much less likely to breakdown, not impossible, but unlikely. Even though your battery seems ok, I would still suggest changing that unless it is very new. Do the simple stuff first.

[DJB72]

Hi….The intermittent non starting problem persists and the issue has been diagnosed to be a fault in the microprocessor located behind the instrument cluster. Two separate companies have arrived at the same conclusion. They have attempted to reprogram the microprocessor with no success. I’ve been advised I need a new microprocessor and that needs to be reprogrammed and coded to the ECU. It’s important to note the most recent specialist to test the microprocessor did not charge me and the original specialist has offered me a full refund once the issue is rectified, so I’m confident their diagnosis is accurate and in good faith.
Is it possible to buy a used instrument cluster and have it reprogrammed and coded to the ECU, or is it the case, as I suspect, this has to done by a Jaguar main dealer with a new cluster? The cost of a new cluster is in excess of £1500 plus the charge to reprogram it. Any help regarding a company that can carry out this task or if it’s even possible would be greatly appreciated.
Thanks

[andypryce]

Ouch. First you would need to remove the offending unit so you could check exact part number, then see if you can get a replacement one from a reputable breaker such as Auto reserve. You would need a good independent jaguar specialist with the correct equipment to programme it to the car yes, it's not just a simple swap. Try and avoid main dealer if you can as independent should be a lot cheaper. Good luck.

[DJB72]

Thanks…..So at least it’s possible to reprogram a microprocessor in a used cluster. That’s good news! I have removed the cluster so I can get the part number. I think the challenge will be finding a Jaguar specialist who is able to reprogram the microprocessor once I find a used cluster. I shall post an update once I source another cluster. Thanks again.

[andypryce]

Contact your regional Chair of JEC, there will be an independent with the correct equipment locally I'm sure.