How do I troubleshoot a car that was driven into a barn under its own power but now (23 years later) does not start?

Hello,

Since this vehicle has been sitting for such a long time, there could be any number of issues you might have to fix.
So, it is nearly impossible to say what would be the minimum fuss/expense.
It could be any defective component(s).

The best course of action would be to first install a new battery, then test all the fuses and replace them as needed. That could help with not getting power to the dashboard. Also, all those relays need to be checked and tested.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

If you are getting power but it is not starting, then check for sparks and fuel.
Also, there is a good chance that the fuel lines are dried out and could need replacement as well as all the vacuum hoses.

See if you can source a repair manual for this vehicle, as that can help with many issues.

In order for us to provide you with some insights, you will first have to inspect the vehicle and let us know what you have found and what is not working or missing. Then we will have an idea of which areas to diagnose and repair.

Let me know of any questions.
Thank you.

That sounds good.

For that price it could have been worth it as a project.

Thank you for using 2CarPros.

I personally like these old XJs. Overall has a unique appeal compare to the later year ones.

I had experienced the V12 XJS, smooth as silk torque curve.

Let us know when you find the next one :)
We are here for you.
Thank you.