I've just got my 94 XJS V12 out of storage for the summer - I use it less than 2 months a year and it only has 24,000 km (real) on the clock.

The problem is most of the electrics are dead. The horn, the windows, the brake pump, the gauges, the indicators, the wipers (but not the washers??). All these fuses can't have blown simultaneously and the ones I've checked are OK.
The battery has been out all winter.

It started first time by the way.

This has to be something central and common to all these multiple systems.

Any ideas where I should start? Thanks for any advice.

 

Well starting with the fuses wouldn't be a bad idea,

Another thing would be to check major grounding points, since some of these may share a ground

 

I agree. Check and clean all the ground points. I did that the weekend I brought my Jag home.

 

This may not be relevant on the facelift cars, but on mine there is a main load relay, in the boot near the ECU, that is activated by the ignition switch. This powers up just about everything in the cabin/instruments. If you have one of these, maybe it has jammed or is otherwise not functioning as intended?

Greg

 

All the fuses appear to be fine - and 90% of the electrical system have gone, I can't imagine anything blowing that many fuses and the car not burning to the ground. I assumed it would be something common - a ground or a central relay or circuit. And you guys have given me places to start.

Obviously I was hoping for the answer - It's the "X" relay situated "Y" under the hood. They're $2, replace that and everything will work fine... But hey, it's a Jag.

Thanks for all the help. If I have any luck I'll pass on anything that may help others.

 

To anyone having simultaneous multiple electric system failures.

There is a ground on the drivers side LHD (it is mirrored on passenger side) that is attached to the small bulkhead the seat is on and is under the cover that protects the car seat control unit. It is between the Seat CU and the inner sill and quite difficult to see. My ground was badly corroded - probably because the carpet that touches it could get wet when it's raining and you open the drivers door.

I think I once left the window slightly open during a rain storm - that wouldn't have helped.

It is in a perfect position to corrode.

I cleaned it, ran the car for about a minute - nothing worked. After 15 seconds the blower sprang to life. Then everything worked.

To show you how important this ground is this is what started working.

Lights (flasher worked before this fix)
Wipers (washer worked before)
Indicators
Radio
Heater/AC
Power windows
Gauges (Oil pressure worker before)
ABS brakes
And god knows what else.

It is a skinny little ground and yet it has managed to cause me much pain.

Hope this helps.

PS - I made a mistake in my original post - my car is a "92" XJS V12 conv.