The Stovebolt Site Forums The Shop Area The Electrical Bay Dimming Lights

I'm not sure if there is a problem here but thought I would ask. The lights on my 1950 3600 6v truck will dim to just about visible when I stop at a light or stop sign, rather when the truck is idling. Step on the gas and get the generator spinning and they brighten right up. I would think that the battery alone would have a enough juice to keep the lights somewhat bright when idling but it doesn't, at least not on my truck. So I wonder if I have a short somewhere in the lighting circuit and I have checked the wiring for the lights to see if there is any continuity to ground and can't find any. Some years ago I replaced the original light switch with an after market unit since it would get quite hot and I thought I had a switch that had some high resistance contacts in it. So the dimming thing makes me wonder if there is another problem. Any ideas?

Check your grounds from battery to frame and from frame to motor that they are attached to clean metal and tight.
Also the light harness on fenders also have grounds worth checking. Make sure battery connections are clean and tight and at the generator. See if belt is tight also.
Good luck.

One part that's notorious for getting a high resistance connection is the dimmer switch. It's down there in a very unfriendly place, and it gets lots of road splash and salt, etc. Try running a temporary wire directly from the battery to a headlight, and see if the light brightens up that way. If it does, backtrack one connection at a time until you find the bad connection. It doesn't take much resistance to create a marginal connection on a 6V system.

The old school fix for dim lights was a headlight relay that took most of the load off the headlight switch and dimmer switch. They're still available, I think.
Jerry

IMHO it sounds normal. That's one of the downsides to a generator and the main reason I put a 6v alternator on my '38. Lights at 8v will be brighter than lights at 6v. At idle your generator isn't charging so when you rev it up the lights get brighter. My '62 Biscayne which has a generator does that as well.