I found that I had three electrical problems. The interior light would blow the fuse when I switched it on. The turn signals did not work, and the third very weird one was where some of the gauge lights would go on when I hooked the battery up but they would go out and others would light when I turned on the rheostat for the lights. As I said - weird! One bite at a time, I began chewing on the problems.
First bite; I took out the string of lights from behind the dash and just hung them on the passenger side floor. Not an easy process. I had to pull the radio first and sacrifice a good bit of skin from my hands, but I finally fished them out. I still had the weird problem, but at least by seeing them there by themselves I could eliminate any wires shorting up under the dash, or crossing off one of them causing the grief. I spent an hour with the volt/ohm meter checking grounds, power input, and power output. I got real good at judging how big an arc off the battery I could draw before popping one of the fuses. A little arc was OK. A somewhat large arc and you could actually hear the little TINK noise as the fuse under the dash blew. The first fuse I blew here was an original Lucas fuse. There were several more non-Lucas sacrificial fuses that gave their very short lives to the pursuit of solving the Lucas mysteries.
I finally traced one problem down to the purple/white and purple/black leads being reversed at the interior light. Apparently turning on the interior light switch would induce a direct ground to the power lead which would pop the fuse. It took me a while to figure that one out because while in the process of trouble shooting the interior light thing popping the fuse, the light itself actually burned out. One of those bullet style lights that took a while to find at the local auto parts store. The stripes on those purple wires are very hard to see, so that was a simple mistake. Reverse the wires, hook everything back up and now the interior light works without blowing a fuse. One bug down.
I continued on with the volt/ohm meter but I was really stuck on this one. Seems that there was partial voltage somehow feeding into the ground plane and back feeding into those lights. After going over the wiring diagram I figured out that those lights should not be on at all unless the other light switch was on as well. Knowing that made the tracing back of the foreign voltage a little easier. I finally hit pay dirt when I found that the face of the Amp gauge had partial voltage to it. Hmmmmm. I pulled off the mounting bracket from the back of the dash, (again sacrificing more hand skin) which I had previously carefully wrapped in electrical tape so a stray wire would not cause an arc. (I had learned that trick the hard way on my first cat - a 1966 Corvair Corsa Convertible. A stray wire on that car caused many dollars to be released from my very thin High school student wallet.) But back to this car. I pulled the wires off the amp gauge and found that the partial voltage was coming from a partial ground which was coming from the impartial alternator. So when I unplugged the alternator, the problem went away. But this did not make sense. Ha, ha! Here I am trying to make sense out of a Lucas problem. Silly me!
I pulled out the amp gauge and could not see any crosses, grounds, or shorts. But I could read one with my ohm meter. I pulled the wires off the gauge and got out my magnifying glass (I use that a lot these days). After careful examination I found that there were tiny little steel filings around one of the posts on the amp gauge that were shorting the post past the phenolic insulator to the base of the gauge! Of course, it happens everyday, how silly of me... what the heck? I don't know where the filings came from. Apparently there is some residual electromagnetic magnetism created around the back of an amp gauge with all the current running through it. I took an old toothbrush and brushed off the filings and then taped up the back of the gauge so no future filings could gather again. I don't know where the filings came from, probably from sitting it down on the work bench at some time. Weird for sure!
Next - Europa Euphoria, Part 28
