I have a 2001 XJ8 108,000 miles.

Recently pulled it into the driveway to wash and vacuum. Immediately following, the car wouldn’t start. All power functions appear to be working (lights, power seats, radio etc.) but there is no response from the starter.
Turing the key in the ignition there is a noticeable ‘click’ from the console but no response from the starter.
This happened recently and our mechanic put a rebuilt starter in it. The problem appeared resolved but then returned weeks later. A tow truck ride back to the mechanic and a day later he got it to start. I was told the gear shift was not fully engaging and that was not allowing it to crank.
It drove for a short time until this past Sunday.
I have tried to move, force and better engage the shifter into park…no success. I tried to start from Neutral with no luck. I’ve got three different keys and tried them all thinking there might be some kind of security feature in the key that had failed. No luck.

Any suggestions would be appreciated.

 

Start measuring from the basics. If you can. Measure starter control voltage at the starter when connector is not removed. If there is control voltagge and solenoid is making strong click sound, is there then earth to the engine and is there then B+ voltage at the starter.

 

This happened to me. Tried every thing ...finally realized one of the battery cables needed Tightening.

 

You could also try swapping a starter relay with one of the punitive relays in the trunk such as a rear fog light relay and see if your issue is resolved.