Here's one for the sparkies. I'm stumped for not just a fix but to understand how this problem can possibly be happening.
Before this story starts everything worked fine in the lighting department in my '66 coupe, except for the dash lights which were pretty faint. I virtually never drive it at night so this has not been a priority but on last year's club trip to Tassie this issue was a bit annoying as we got off and on the boat in Devonport in the dark. With this year's trip coming up I thought I'd address this and install some LED dash lights.
That all went fine apart from some scratched hands fiddling around behind the dash and I thought I'd install a new headlight switch while I was at it. I wisely decided to test it all before buttoning it up again. Dash lights are great, enormous improvement, the rheostat in the switch works nicely adjusting the brightness of the dash lights - but no headlights!
Weird!. I have dash lights, I have tail, stop, parkers and indicators, but no headlights. I have a relay kit in the headlight wiring so the full current isn't going through the switch, maybe the fuse in the relay kit has blown for some reason so I check that but its fine.
Then I checked whether I had high beam. Sure enough, that's fine. Here's where it gets strange. When I hit the dipswitch again the high beam indicator goes off as it should but the lights stay on and as far as I can see they are still on high beam (bit hard to be absolutely sure without risking blindness). Turn the lights off at the switch and then back on. Nothing. Hit the dipswitch and on they come on high beam. hit the dipswitch again and they stay on but indicator goes out.
So I put the old headlight switch back in and test - exactly the same result. Note that this problem didn't exist before I started this project. I know this because as well as the dim dash lights the headlights were seriously out of alignment and I had been adjusting them in preparation for Tassie a couple of weeks earlier. Put the new switch back in and still the same.
So now I think maybe the dipswitch has developed a quite coincidental problem and ordered a new one. Until I could get that I tried bridging the terminals on the plug that connects to it and taking it out of the equation. This reproduced the same problem, indicating to my electrically challenged brain that neither the headlight switch or the dipswitch is the problem, but I put the new dipswitch in anyway and still have the issue.
So can anyone explain this? It makes no sense to me. Even the possibility that the LED bulbs are interfering with something doesn't seem to me to explain what its doing. I could test this by removing them and putting the old incandescent bulbs back in I guess but would rather avoid the hassle.
As things stand at the moment I could drive it at night by turning on the lights and hitting the dipswitch twice but I'm pretty sure I'd be stuck on high beam. If necessary I can adjust the lights down as far as I can to avoid blinding other drivers and it'll probably be OK for the short night time driving in Tas in a month but I'd really rather both understand and solve the problem properly.