The Stovebolt Site Forums The Shop Area The Electrical Bay Headlight switch

I believe the headlight switch on my big GMC is bad. After working on the harness install for while I finally got power to the switch but nothing coming out of it. http://s1366.photobucket.com/user/M...g1_zps1rxugrs9.jpg.html?sort=6&o=228
I checked it for continuity but get nothing. I found a few on Ebay but if they were used, no one claimed their switch was tested and if nos, they wanted 150.00!! I don't have a problem going with an after market or non-original switch either, just one that will work and I can use the correct knob on. Or, is this switch repairable??
What is interesting is, it looks like they used this same switch for a long time and in many different models. I even saw what looked to be the exact same switch listed to fit a 54 Corvette.
Thanks for any suggestions you may have.
Billy

I have taken switches apart and cleaned the contacts.

How many times have you broken the tabs that are bent over Charlie???

I've found that the biggest problem is the Bakelite sliding
block breaks in them causing uneven pressure on the contacts
and the brass rivets corrode or become loose, resulting in
poor or lost continuity.
When it comes to the dash lights, corrosion is especial bad at
the copper at the rheostat terminal, or the resistance coil
is open because of a broken wire.

The higher priced reproduction light switch is very close to
the original one and for $48 is much easier than trying to
repair the original switch. The cheaper $24 switch is a piece
of junk.
http://www.classicparts.com/1947-54...6-Volt/productinfo/53-111A/#.VaVQBflViko

dg

If you have a multimeter, check the resistance on either side of the bi-thermal contacts that act as a thermal overload for the switch. You should have virtually no resistance. I have found a build up of corrosion on these contacts that prevented the switch from operating. A simple light sanding got them working again.
Mike

I pulled the switch out and took it apart. Not bad to work on, kind of gritty and dirty inside so I cleaned it up real good. I noticed there are some worn grooves where the brass plate with the dimples in it rubs across the contacts. Put it back together and no change. Not sure what makes that exterior bar with the contact on the end engage with the corresponding contact on the end plate. If I manually make the two contacts meet, I have power to the terminals.
I think at this point I will just pickup the switch Denny linked. Last thing I want to do when I eventiually get this truck back together is have blinky lights, or worse, no lights.
Thanks all for your help.

Bill, the power comes in at the buss, thru the thermal circuit
breaker to the common terminals. The brass slider has three
positions OFF/PARKING/HEAD LIGHTS. This should be clear if you
follow the three color coded positions of the brass contact slider:
http://www.pbase.com/dennygraham/image/160746301/large

Denny Graham
Sandwich, IL

First let me apologize for adding post question to this post. I'm relatively new to this forum and for some reason I cannot post an initial question.

I recently bought a new wiring harness from Rhode Island Electric for my 1941 I/2 ton truck (6 volt system). I've have finished with everything except the headlight switch and am at a loss as to what goes where.

If someone could give a detailed description or post a photo of the various connections I would be most appreciative. My knowledge of electrical wiring is somewhere well below Principles 101.

I paid $600 for the wiring, hate like hell to fry something.

Thanks,
Ed

Thanks Denny. So the thermal contacts should be "made" or touching. In the event there is an over load or fault heat would cause the contacts to break (hey, I'm smarter than the average bear). The contacts on my switch are not and my guess is when my old wiring harness went to the builder (headlight switch included), they attempted to clean it up. I believe all they did was put it in a blast cabinet, thus the grit inside and tweaked that bar a little bit.
New switch ordered and on the way.
Billy

The thermal breaker is simply a bi-metal strip calibrated to
open if to much current is being drawn. The contacts are often
a problem with the original switches.
Sounds like the builder contaminated the contacts with something
or possibly bent the bi-metal spring.
The brass studs inside the switch wear also and can give you
an open.
For fifty bucks your problem is gone and you shouldn't have
light switch problems again for another 55 years.
Just don't try to get by with the cheap switch, it really is
tinny and a piece of crap.
dg

Ed,

Contact Rhode Island Electric customer service and have them instruct you as to what goes where.

Mike B