If you decide to re-cover the the original biscuit, ensure the adhesive is is of a high temperature resistant specification or you'll be doing the job again after the next heat wave :( I can recommend Trim-Fix https://themetalhouse.co.uk/product/trim-fix-500ml-high-temp-spray-glue/?srsltid=AfmBOoqRA...

For me, that's an unexpected question about an X100 Jaguar as I've always thought the headlight lenses to be real glass and needing no special treatment even after many years! :? Both our X types had plastic lenses and they did fog over needing an occasional weekend's time allocation of an appropria...

I've just been out to take a few measurements of my XK8 for your info. but it's not very promising. Widthwise the interior is limited to no more than about 40 inches, but on a diagonal line from rear corner of the parcel shelf, through the gap between the front seats towards and into the passenger f...

I think the most indelible copy of the VIN is machined directly into the structure of the car immediately to the righthand side of the battery, just under the edge of the trim panel

The brake cleaner method may work if you're lucky, but I suggest a more positive approach would be to do a smoke test that blows smoke out of the smallest cracks and crevices. If you're handy, there's even how to build a DIY smoker on You Tube Two pipes not to miss are those of the crankcase breathe...

There is one fuse common to the four up/down relays that safeguards the supply to their operating coils and that is F1, 5A in the Trunk Fuse Box. That seems like an easy starting point, but as the Down circuits did work, it's maybe not so likely to be the root cause. There's also the two fuses, one ...

This is taken from the Jaguar Manual
The whole manual can be found here

http://www.jagrepair.com/images/AutoRep ... ervice.pdf

My first step-up from your screwdriver(?) blade approach would be to replace the blade with a metal door trim removal tool that's thin enough to get under the bolt head on both sides at once giving with a better distribution of upwards force while rotating the bolt. That's the sort of tool with a U-...

There should be 70 pulses per revolution that presumably are met by your 35 peaks and 35 troughs. The general sensor supply voltage to the engine control system is a nominal 5v, so peaks and troughs of 4.76 in total sounds about right while a 10 per cent increase during the longer pulse at the marke...

The rubber cap looks like one style of the caps that are fitted over various projecting screwed studs for both their protection and yours :D, but it is rather larger than any I recall seeing anywhere on my XK8. If the rear height sensor is repairable, that may well be your best way ahead, otherwise ...

The total quiescent current from the battery, with the car fully asleep, should not exceed 30 mA. With that much being taken by the sounder, the total must be too high and part at least of the excess must be the sounder itself. As it has a connection to the BPM and a ground wire, a drain might still...

I'd go with that advice to get to a good starting point for what's to come. Somewhere along the line it looks like your you're going to find an underlying problem with the CAN bus system and maybe the SCM one too as indicated by the P1798. That could be fun! For the AC problems. start here if possib...

Sorry I can't add anything to help Mark's ideas along, so some other thoughts that have come to my mind. If the various faults are not inter-related, then the engine start problem could just be the starter relay or its fuses. The relay is in the driver's side enclosure. Exactly where is shown on Pag...

Looking through the electrical diagrams for some signs of commonality for your faults and it may be of relevance that the fuel flap, the boot release, the Ignition Key IN switch and the Not-in-park switch all share a common ground point. Not-in-park would prevent starting. You might try getting roun...

Could it be that the Inertia Switch, in the passenger side dash fuse box, has tripped?