I have a 1937 1/2 ton pickup that is basically original except that it was converted to 12 volt when the original harness (which was in shambles) was replaced. The headlight buckets and wiring system are the same as original except for using 12 volt bulbs. Here’s the problem: the passenger side headlight shines strong and bright, but the driver’s side headlight shines at about 1/3 the brightness of the passenger side. I’m assuming that this is some sort of grounding problem or a bleed of some sort.

If you have ever worked on a 37 or 38 truck headlight, you know that it’s a major hassle to remove the headlight bucket and or stanchion to get to the underside of the light where the harness enters the bucket (the radiator and stand are in the way, along with portions of the grille shell, etc.).

My question is whether there is a solution to my problem that can be achieved by working through the front of the headlight, i.e., by removing the headlight rim and lens, and reflector if necessary, without having to remove the entire headlight bucket from the grille shell? Any suggestions will be welcomed. I don’t drive the truck at night very often, but it would be nice to have both headlights working equally well.

Thanks in advance for your help.

Jim

The first thing to do Jim is to trace the fault. With the headlamps on take a loose earthed wire and earth the reflector at one of the mounting screws.If it brightens up remove the reflector and install the earth wire between the reflector and a radiator mounting bolt.

Wannchev,

Thanks for the suggestion. I removed the rim and lens and attached a ground (earthed) wire as you suggested--no luck. But in doing so, I discovered that there is power to the reflector itself on the driver's side! Obviously, that should not be the case and is the source of my problem. I checked the properly functioning passenger side reflector, and no power to the reflector there, with functioning bright light. So, it appears that there is some sort of power bleed into the reflector itself--I haven't dug deeper, but but before I do, does anyone have a suggestion on how to isolate and solve the problem?

Power to the reflector means the reflector is not earthed . Current to the reflector is first passing thru the lamp filament and then the reflector but it cant find earth and get back to the battery. So the lamp stays off. Got to find a clean earth connection.

Problem solved—you were absolutely correct. Found a way to establish a good ground and now I have a bright headlight.

Thanks, wannchev, much appreciated!