I have recently acquired a 92 XJS and the previous owner had to install a battery shut off switch in the trunk as he was unable to get the headlights to shut off. So it’s a real pain to have to remember to switch the main power every time you want to move the car.
I inspected and cleaned the directional mounted headlamp switch. It’s pretty simple and while disassembled the headlights remained energized. So it can’t be the switch. The high beams are also always on with the indicator light on the dash lit up.
I’ve looked at the wiring diagram in the book and it looks like the relay could be closed for both… is that right? Is it likely the relay?
Also, there had been mice in the engine compartment which chewed one of the injector wires. We replaced those during tune up and the engine is running smooth. However there could be more hidden damage.