Hi All I need some help on this one ive got some quite odd problems

The backstory

The dash has been fully out to do the AC Expansion valve replacement & fully reinstalled. Upon every step i took detailed photos and videos of wiring and plug locations I am now very familiar with the under dash landscape.

The car is now fully reassembled. I took it for a test drive and the symptoms are

*Tachometer is not working at all,
*The fuel gage reads correctly while cruising
* On medium / hard acceleration the fuel gage bogs down to zero
* in sport mode flooring it didn't seem to have the same kick down.
*the tach does do a tiny wiggle on cracking
* There is no check or warning lights or messages
* All other instrument functions are working perfectly.
* I Do not have a transmission warning light displayed

Steps i have already taken
* Under dash plugs checked 3 times over
* ECU & harness header plugs checked for moisture ( all perfect as I'm in New Zealand and its a garaged car )
* Fuel sender unplugged and tach still not working
* Instrument fuse and Relay in LHS rear fuse panel checked and found to be fine.

Steps i have not taken
I have not been scoped on the cluster header plug to confirm the 5v 15hz @ 1000rpm
I have not checked continuity on the wiring loom from point to point
I have not inspected the cluster for damage possibly from installation.

I've just struck the issue where my I-CAR soft I930 wont communicate with the X300 as mine is a 95 so reading codes is not possible

Ive read the other thread about tach and fuel gage in the XJR but there wasn't really a decent resolution noted

https://www.jaguarforums.com/forum/x...orking-104180/

its behaving like a plug in backwards or a pin grounding out that shouldn't be, something is up and I'm really stuck

any thoughts would be much appreciated