73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Electrical => Topic started by: fiddler on April 16, 2026, 01:57:48 pm
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I have a titled 1974 chevy C10 with parts from a multitude of vintage. The switch that turns on the dome light when you open the door (door jam switch?) has failed. Turns out the spring has springed too many times and is now in pieces. So I ordered replacement from truck. it's too long. It appears the 1973 and 1974 model switches were shorter. Does anybody have a source for these switches? The tube after the hex area is proud by .23 inch. Suspect was supposed to be .25 but is appears a bit mushrooomed by 52 years of opening and closing the door. Thanks in advance for your help.
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The door jamb switches are generally self-adjusting to length. The switch sleeve inside the barrel nut is designed to slide inward toward the jamb the first time the door closes, setting the plunger protrusion to the proper height.
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The barrel on the 74 protrudes 1/4 inch from the hex portion. The plunger is self adjusting of course but on the 74 the 1/2 inch barrel is too long for the door to close. I suppose I could "adjust" the point where the door closes over the switch with an inline shock adjustment tool, but denting that part of the door 1/4 inch is a last resort for me. I am also planning on replacing the doors this summer and would rather not start out by denting the new door for the switch.
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OK after tons of research I now suspect the old switch has been modified to work. It is not the correct switch that is called for on all of the vendors I find. The switch is probably a newer model switch cannibalized from a junk yard and the barrel cut down to fit. The connector has been changed. Remember this truck is a hybrid of years. I am going to try the original switch from trucks for the 1974 year. I originally ordered by how the switch looked as I can't depend on the year of the title for parts with this truck. I suspect the original plug was removed and a spade put on the wire to make with a later model modified switch. (use what you have or junk yards are cheaper or??) Anyway, I will try to find a connector for the new switch and get that on the end of the wire. Looks to be a bullet as opposed to a spade. Thanks for any responses.....
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Maybe I'm not duplicating your question or the problem. Look at the attached image. The sleeve (or barrel) is snug, but slides axially through the hex nut. When the door initially closes on a new switch, the door presses against the plunger, the mushroom head of the plunger presses against the end of the sleeve, pushing the sleeve through the nut into a new position that sets the plunger height, allowing the plunger to slide in and out according to whether the door is closed or open.
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Yes, the OEM switch used a bullet terminal. And, I agree, it sounds like the switch was replaced with a newer design configured for two spade terminals.
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I have the correct switch and some bullet terminals coming. I get now what you are driving at. It is indeed a self adjusting switch! Clever those americans!!
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So I found an adjustable switch on Amazon and installed it and it works great. I am still impressed with whoever managed to cut the old switch down to fit. The switches from el m see truck do not work on my truck. It may be because the doors are from different years. (Newer doors from a junkyard because the old ones rusted out??). So the trick seems to be to find a switch that has the barrel made of a different material than the threaded portion of the switch. Also have to ensure the threads go all of the way to the hex part of the threaded section in part with no gap at the hex. The switch I bought has a silver colored base with what appears to be a copper sleeve and a silver colored plunger. If you order these be advised there is also a set of two available for a lesser price than two single switches. The set appears to be the same switch. Wish I had seen it before I ordered two singles. Thanks for all of your help!