If you've got the original light switch in the truck, it's probably the rheostat gone south on you. They corrode where they are riveted to the ceramic block; the connection builds up resistance causing the coil to over heat and eventually burns the coil out. If your starting to have problems with your dash light dimmer then it’s just a matter of time before the headlight contacts start giving you trouble, they are copper also. This is a sealed unit and not meant to be repaired.
I have rebuilt a few but you have to make new internal contacts for the headlights, and for the dimmer coil at bare minimum you need to replace the copper rivets and in a few cases I’ve had to rewind a new coil with a special resistance wire. Also the dimmer coil is potted in a special high temerature ceramic and this works loose in the old switches. Loosing your headlights can be bad if you do any nighttime driving with the truck, been there, done that.
Best thing to do is replace it with a new one from the vendors, your choice of vendor but here is one example. They offer two, the one to get is this one:
http://www.classicparts.com/1947-54-Headlamp-Switch-Original-Type-6-Volt/productinfo/53-111A/ it runs about forty five dollars. I’ve used them several times before and they are exactly like the original ones, one of the few reproduction items that is well made. There is a cheaper one for twenty five bucks but its really chinsey, like its made from tin cans.
Also, if your having trouble with dim yellow headlights, I mean if they are not as bright as your buddy’s 12v system, chances are that the headlight contacts are getting corroded and you’re dropping some of your 6v’s at the switch because of the resistance. Also while you’re at it, it’s only a couple of bucks more ($7.95) for the headlight foot dimmer, good idea to replace that now and you will have a good reliable, bright lighting system that you won’t have to worry about for years to come. Remember, the chain is only as strong as it’s weakest link.
http://www.classicparts.com/1947-54-Dimmer-Switch/productinfo/53-211/ Denny Graham
Sandwich, IL
