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I put a full new wiring harness in my '46 and everything works except for a problem with the headlights. Whether they're on high or low beam, the high beam indicator lights up. I thought I followed the instructions, but there were other mistakes I caught. I unplugged the bulbs and everything acted like it should, so there must be a backfeed going on through the filaments because the ground is not correct.
My question is: which terminal on the sealed-beam bulb goes to ground? As I look at the back of the bulb, there are 2 vertical terminals and one horizontal terminal and I'm not sure which should be grounded. I know I could play around with it, switching wires, but it's easier just to ask first.

center is ground [horizontal], but ground won't cause the indicator problem unless something is causing hi and lo to be on at the same time ... standard wire colors are black for ground, green for high beam, tan for low, and there should be 2 green wires from the dimmer switch, one to the lights, one to the indicator, so the indicator is only powered when the high beams are powered, sounds like you may have that [green] wire to the indicator hooked to the terminal that brings power from the light switch [blue]

Bill

Looking at back of bulb with one terminal across the top and one vertical on each side, the left one is GND, top is low, right is high. That would usually be left: black, top: red or red/wht and right: grn or red.

well I have been known to be wrong, but that would just mean whoever drew the wiring diagrams blew it because all years show the center terminal grounded .... and for sure the colors are green and tan

Bill

Had this in my files: [IMG]http://i279.photobucket.com/albums/kk158/bartamos/headlight20plug.jpg[/IMG]
Must be modern or not Chevy. But I thought I used it on my TF rewires and that's why I kept it. Sorry if it's wrong..Here is one on ebay right now advertised as 1938-1950 and looks like the colors and hookup I described. [IMG]http://i279.photobucket.com/albums/kk158/bartamos/KGrHqJHJFUE-k8ohRKkBPvmcelg60_35.jpg[/IMG]
Jim Carters 1934-1946 headlight socket is the same as pictured on Ebay.

well there weren't any fiberglass trucks in our era and all the big bulbs I've seen have 3 pins the same size, but an ebay look finds H4 connectors with colored wires that show the black on the right

Bill

That matches black on left looking at back of bulb, my pic. Oldmanuals for 46 truck shows BLK natural, GRN natural and natural. What the heck is natural? Neutral? and they call everything a "tracer". I think maybe tracer and crossed tracer means striped (two color or ridged)

Thanks, guys. I hooked the horizontal terminal to ground and it don't work. I found a couple of diagrams that agree with the one bartamos posted. I will try that and let you know.

As far as High Beam indicator: As Bill has said, The dimmer switch just gives power to one filament or the other on headlight. Dimmer has three terms usually. Again, as Bill said, BLU GRN TAN. Don't know if your "new" harness follows this. I would think so. Anyway, one is hot supply to the dimmer (center terminal), either of the other two can be Hi or Lo, So whichever terminal on the dimmer switch makes high beam, that's where you hook the indicator feed. Just use a tester to see which term is hot when beam is high... After you figure out the socket wiring. NOTE: As always, you must be sure you have good, direct, clean metal ground from the socket ground to the chassis and everywhere else. you will have constant electrical problems without many good grounds. I know you know that. These posts are read by many others.

Well, I got it fixed. The low beam and ground wires were reversed. This allowed the high beam filament to back-feed to the indicator. Either the instruction sheet was written wrong or I read it wrong. It can be easy to mistake black and brown wires, but I did the same thing on both sides.
I want to thank everyone for the suggestions. The color codes didn't help because the low-end wiring harness didn't even match the direction sheet, let alone factory colors.