My 86 XJ6 SIII has a "sometimes" problem with the high/low beam switch. Some times it will work normally, other times it will not switch to the other mode. It is currently stuck with the high beams on, but only when the headlights are on...pulling back on the switch won't activate the lights for a "flash to pass" occurrence.
Normally, the switch would make a click when switching, but now there is no click regardless how many times you pull it back. It might stay this way for weeks, only to start working again (and with the switch click). The click is in the switch and is not a relay, it seems like something is no longer physically working right.
I've read several of the threads on similar issues, but most seem to be electrical in nature. Any easy way to check the switch's functionality?

Jim M

 

If mine was doing that, I would take the cover off, put plenty of absorbent towels below, and "clean" the switch with WD-40 (a non-conductor); or something similar, "washing" it out well. This will also lubricate moving parts.

I would first suspect the mechanical toggle activator inside before I start messing with electrics. But then, I understand mechanicals better than I understand electrics. If that doesn't work you can always take the switch apart, but I always try the easiest thing first.

Very often something simple is wrong with switches like that, they get dirty or the original lubrication dries out, and all they need is a little light weight slip-free applied internally and they operate flawlessly for another couple decades.
(';')

 

Another approach is to earth the blue/black wire at the headlight relay and see if the relay operates reliably and switches the lights. If that works you know it really is the switch (or wiring back that way). If it doesnt work you have a dud relay. Just need to test when its in a bad mood and has stopped working.

 

I feel that the problem is in the physical switch itself...like I might have mentioned that it no longer clicked or had the same feel that it has when it works. The switch works sometimes, but when it doesn't I'm forced to keep the same state of lighting, either always low or always high beams until it magically decides to grant me another working switch.

Jim