Last week I took my XK8 to the local Jaguar specialist to have rear bumper and front wing resprayed and whilst it was there I mentioned the surging from the transmission from cold.
It was suggested by the mechanic that this surging might be reduced by a software download from latest available SDD program, and so left it with him to carry this out. Unfortunately when came to pick it up it now had gearbox fault warning and was also in limp home mode.
It would seem that having wiped the existing software in the transmission ecu in preparation for the update, the ecu would not except this update so leaving the gearbox in its present state.
So far he says he has checked the earths, wiring connections, canbus system and has found no fault. He has also contacted Jaguar Independent support services(the software is genuine SDD version) they could find no fault with this software version.
I'm at a loss at what to do next(after phoning Jaguar Customer support they suggest taking it to an official Jaguar dealer for diagnosis), the car is still with the specialist. Both Jaguar and the mechanic seem to be puzzled why the ecu will not except the download, has anybody come across this problem before ?

 

With the mechanic having no luck solving the gearbox fault, I decided to consult with another Jag specialist, he suggested that if the car starts, the gear change display lights up and the car drives, he may be able to recover and download the jaguar software(the car was stuck in third gear BTW).
I then drove to the other mechanic's garage but when he connected the SDD laptop to the car no matter what he tried, there was no communication to the box, so he then suggested that the mechatronic unit was at fault in the gearbox and would need replacing.
Reluctantly I returned to the first specialist and he then suggested removing the mechatronic unit and have ZF reprogram it with the original software it left the ZF factory with.
This has now been tested at ZF, but they could not find any fault with unit's software so I am now back at square one.
It seems strange that the car starts and drives quite well considering it is stuck in third gear with the gearbox fault warning and engine management light illuminated, yet will not communicate when connecting to the OBD plug. Would anyone have any suggestions what check next?

 

Well, the first so-called mechanic(AWJ Ltd) had the car for 5 weeks without solution(managing to remove the dash veneer covers in a effort to find a problem with the car wiring which didn't exist and cracking the windscreen in the process!)
Eventually I had enough so recovered the car via my insurance breakdown service to Jaguar specialist (XJK Ltd )who advises the national JEC on technical matters, he diagnosed a corrupted mechatronic unit in the box.
Ian(head mechanic at XJK) suggested that it may have been corrupted when AWJ could have interrupted the software download by letting the car or laptop battery voltage drop too low, or disconnecting the diagnostic lead part way through the download.
Within 3 days he sourced a 35000ml gearbox and back flushed it through then fitted it.I now have car which changes gear like a new one and even the surging when cold is gone.
In all this has cost me £1300(plus the insurance windscreen excess) and finding out the difference between ignorant cowboy of a Jag specialist and the font of expert knowledge that is Ian at XJK, the difference between these two is like night and day ....ah well I know who to visit in future.