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Odd wiring problem

Posted: Tue May 12, 2015 12:14 pm
by Steamerpoint
This one might be obvious to some.

Last night while putting petrol in, some spilt on the rear wing. Just a few drops, so decided to give the wing a quick wipe with a clean cloth before driving off. The cloth brushed past the brake light lens, which promptly disintegrated obviously due to over tightened screws. I noticed at the time that one of the wires had been held in place by a lens cover screw. Anyway, unable to do much about it at the time, threw the lens on the back seat and carried on. A few miles further at the MMOC gathering we obtained and used some electrical tape to hold the broken lens cover back on.

Later that night when I got home in the dark and turned the ignition off, I was surprised to discover that the side lights, speedo lights and oil temp guage lights were still on! I am not really sure where the switch is for the side lights as it goes, but tried various things to turn these lights off, eventually resorting to pulling the neutral cable off the battery (As this one is loose enough to pull off by hand) and calling it a night.

Is it possible that the brake light and possible loose wire could have caused this odd lighting experience?
Perhaps one of us have accidentally found a side light switch somewhere and switched it on!

Two new brake lenses on order from ESM, which I'll fit tomorrow and have a closer look again then.

Re: Odd wiring problem

Posted: Tue May 12, 2015 12:52 pm
by simmitc
Many odd things are caused by earth problems. Firstly, your main battery earth cable should NOT be loose enough to just pull off, the clamp should be tightened with a spanner. Secondly, the side lights come on with the first click of the main light switch. Second click is the headlamp. early cars were pull once, pull twice, push in for off; later cars up for off, horizontal for side lights, down for headlamps.

It sounds as though your rear light was using the cover screw as an earth. there should be an earth wire from the back of the lamp unit through the wing and inside the car. Search for "wiring diagram" to get a good look at how the wires should go, and then use a meter or a bulb to trace what is what on your car. Good luck.

BTW, modern lenses tend to be rubbish, either not fitting properly, and/or dissolving in petrol. :evil:

Re: Odd wiring problem

Posted: Tue May 12, 2015 1:00 pm
by Steamerpoint
Thanks. Yes it is a 1956 moggy, so perhaps I need to play about with the main switch some more. The earth cable on the battery was fairly tight, but a big pull and a twist can remove it. I made the mistake of going out without any tools! Doh Doh Doh! :oops:

Re: Odd wiring problem

Posted: Tue May 12, 2015 3:01 pm
by Steamerpoint
Update. Yep it was the light switch. It doesn't like going straight back in and stops with the side lights on. Needs a bit of a wiggle to push it fully home. Sorted.

Earth cable on battery nice and tight now too. :D

Re: Odd wiring problem

Posted: Tue May 12, 2015 3:13 pm
by amgrave
Mine is a 63 and has a push pull light switch. It does not go straight in and out though you have to pull it out for sides then twist slightly clockwise and pull some more for mains then reverse for off, push in to turn off mains then twist anti-clockwise and push in again for sides off. Hope that helps.

Re: Odd wiring problem

Posted: Tue May 12, 2015 8:37 pm
by Steamerpoint
amgrave wrote:Mine is a 63 and has a push pull light switch. It does not go straight in and out though you have to pull it out for sides then twist slightly clockwise and pull some more for mains then reverse for off, push in to turn off mains then twist anti-clockwise and push in again for sides off. Hope that helps.
Yep, that sounds about right. I expected to simply pull it right out and push it right back as a 2 position switch. It never occured to me that it was a 3 position switch, which needed a twist half way through the positions. The joys of a new car!

Not sure what the previous owner has done with the main beam lights though. They are the brightest headlights I have ever used. seriously bright.

Re: Odd wiring problem

Posted: Tue May 12, 2015 9:44 pm
by simmitc
When you've worked out what's been done to the headlights... let the rest of us know so that we can upgrade too :wink: