A month or two ago I bought a '94 Jaguar XJ12 for almost nothing because its owner wanted it out of her garage. I got no remote for the door locks or the security system. It hasn’t run in two years. Battery was stone dead. I put oil in the cylinders and tried the starter with a new battery, got a heavy click like a relay, but no crank. It does this consistently. All interior lights, etc. come on fine, but no starter. Might be a failed starter or solenoid, but it seems different. I know the car has a Jaguar Security System, it has the module just in front of the drivers seat on the floor. Can the security system do this? Assuming the security system can do this, how can I get past it without the remote?
My parents had the same model. I think that this car has an engine immobilizer device as part of the security system. Check the manual, there may be a procedure to turn off the security system using the igntion key. Keep in mind this car features Lucas electics so even if you do everything you’re supposed to there’s roughly a 100% chance that it will not work. Great car when everything is working right though.
I’ll bet a Jaguar dealer can bypass the security system if you can get it there. Call them if you run out of other options.
I don’t think anyone frequents here with a Jag. I would highly recommend googling ‘jaguar forum’ and go from there. The car specific forums typically are beyond helpful although good advice is here too.