1992 headlights won’t shut off


(Greg Heitman) #1

Hi all,

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.

Any ideas?


(John) #2

Your guess of a relay is probably spot on. If you look on the US driver side inner fender, you’ll see a cigarette pack sized relay that might say ”Hella Logic Module” or maybe just jaguar in white lettering … that’s your headlight relay. The part numbers right on it. They aren’t cheap so this is not the kind a part you want to throw out the car if you don’t need one, but they are a source of trouble.


(Greg Heitman) #3

Thanks, John. I pulled the relay and the lights go out. So I suppose that must be it. This one has a handwritten decal that says “socal 7-19-13”. Wondering if this is someone’s repair that failed.


(van Horneff) #4

Greg,
Thanks for posting this and for the solution others provided. I’ve been dealing with the exact same problem and I installed a shut off switch as a temp solution over a year ago. I purchased a used relay, removed the defective one, and installed the replacement in 2 minutes. I no longer have to open the trunk every time I get out of the car to flip the lever on/off.