I can not figure out why when I try high beams on my 1990 XJS, the lights go out completely .
I pull back on the lever again and the low beams come back on. Confused a bit.
What year is your XJS?
Facelift cars have a relay and control module of some sort. Earlier cars have just a relay…so it’s a bit easier to diagnose
Have you checked all relevant bulbs, grounds, and connections?
Cheers
DD
Please take the time to add your model year and engine in a signature so that people can help you. This car was sold for 21 years. If you’re looking for help…help us help you.
My guess is that you have a faulty relay.
Power for the low beams goes right thru the relay. When the relay is triggered power is supposed to be routed to the high beam elements. It looks like that isn’t happening. If all the headlights were recently working correctly a faulty relay seems likely.
The other possibility is problems downstream of the relay. Burned out bulbs, bad grounds, blown fuses, dirty connections. A stack-up of faults accumulating over a period of time, unnoticed util now.
Do you have a test light or meter? It would be easy to make a few quick checks.
Cheers
DD
where is the relay located please?
If this is the infamous Hella relay (I don’t know if it is), you might try “flashing” the high beams with the lights switched off and see if that works. If it does, it’s almost certainly the relay, because the daytime flasher function is a different relay within the same can. If it doesn’t, could still be the relay, but possibly other stuff as DD advises.
I recall that it is right next to the headlight fuse box, LH side of the engine bay
Cheers
DD
Mark,
Attached is a picture of the Headlamp Relay, circled in green, in my wife’s 1990 XJ-S convertible.
I have experienced that problem before and it was due to tarnished electrical contacts inside the relay. I removed the metal cover of the relay, cleaned the contacts with fine sandpaper, put the cover back on, and reinstalled the same relay. It continues to work fine.
Paul
That’s the one, yes
Cheers
DD
thank you very much,you are kind enough to send a nice clear picture of where to look
awesome,thanks again. I also wonder why only the right side dash courtesy light comes on when I push the button.the lamps are both ok, please
Mark,
This is how the Map Light Switch is supposed to work as shown on page 65 of our copy of the 1990 XJ-S Drivers Handbook. It reads “When the switch is depressed the passenger’s map light will remain illuminated irrespective of door positions.”
I have found that having the correct technical data about my Jaguars has taken a lot of the mystery out of owning and working on these cars. Some things, like the operation of the map light switch, are not intuitive. I have no idea why Jaguar designed it this way, but they did.
Paul
“Some things, like the operation of the map light switch, are not intuitive. I have no idea why Jaguar designed it this way, but they did.”
Many British cars of that era had some sort of map light for the passenger. Of course, it was well before the invention of cell phones and GPS, so the passenger would be struggling with huge paper maps. At night, on the narrow twisting B-roads of Great Britain, it was much more important to avoid any light that might degrade the driver’s vision.
Ron,
Thank you for your explanation. That makes sense.
Paul
Said the dark lord, Lucas.