The Stovebolt Site Forums The Shop Area The Electrical Bay Help needed choosing a replacement ignition switch 39 GMC

I am in the early planning stages of wiring up my 39 GMC and the switch that came in it doesn't have a key so I cant get the existing lock cylinder out without hacking it out. Long story short, I need to get a new ignition switch. Looking at my master parts book, I haven't been able to find a NOS switch on ebay but there's a ton of other switches from this era on there.

Back when new, my truck (I think) would have came with an ignition switch with two screw terminals on the back and a 3rd shielded wire that went to the coil. I'm just a little confused because my 39 GMC only has the two screw terminals on the back. I can only assume the switch had been changed sometime in the past and rewired. My truck has a bunch of wiring missing so I'm not sure how the two terminal switch was wired to the coil.

My question is: Do I need a two terminal switch or should I look for a 3 terminal switch?

You might be able to get a key for the switch (if original) by removing the door lock and looking for a 4 digit code on the stem of the lock cylinder. That may match the ignition key. GM used Briggs and Stratton keys from 1935-1966, and a competent locksmith can cut a key from the code. If you can't find one of those (a competent locksmith) check out this post for info on how the keys were cut.

Unfortunately, the lock cylinder is missing from the door.

A good locksmith ought to be able to extract (pick) the lock cylinder out of the assembly and then open it up to cut a key to fit or rekey it. Once that's done, a replacement door lock cylinder can be keyed the same to give you a matched set.

You may have had an electrolock coil distributor set up. If so, you need to revert to a normal distributor and coil. Find a NEW aftermarket switch that fits the hole and looks like you want it to look from the front and has a key tumbler with key. Does NOT MATTER how many terminals it has on the back. A simple ON/Off two position switch is usually hard to find. May have to settle for a three postion and just use two. No big deal.

Let us know about any funky, non original things you are adding or if you are going 6V or 12V. Your GMC would have been positve ground. You should revert to negative ground.

Are you foot start and have a 228??????? Fill us in when the time is right.

Pictures of all your ignition parts you have and the dash, would be very very helpful as well as the few questions I"ve asked.

Like Bart said, it's an Electrolock. If it's the same as a 38 car (or if you could make it work) I might be able to help you. PM me. If you don't already have the Electrolock off of the coil there's a trick to that as well. When you get it off, if you get it off without destroying the coil or cap, grind the locking nub off of the inside of the cap so, in the future, all you have to do is twist the cap to remove it. The Electrolock was the hot wire deterrent of the time.

I know it sounds like a silly question, but how can I tell a difference between an electrolock distributor and a non electrolock? I assume since I don't have that braided cable mine had been converted to non. I am putting in a 53 248. Im not in front of the 248 otherwise I'd snap a picture.

Ultimate plan is to convert to 6v negative ground. I don't plan to add anything that I can think of off the top of my head that's funky or non original. When I get my gauges rebuilt don't I need to have them convert the ammeter or something like that?

I currently have a foot start locked up 228 installed. I plan to keep it foot start.

Daniel - Below is screen grab of an "Electrolock" ignition switch assembly from this current ebay ad for an NORS one. The metal cup on the other end from the lock cylinder part is what attaches to the original style coil shown in Tiny's pictures above. There isn't a difference in "distributors", just the coil.

Your choice on if you're wanting to retain originality (but I see you have other alterations planned) or go with a reasonable looking plain ignition lock cylinder switch. It may be simplest to go with a new keyed switch.

I see. You don't have an electrolock so it's of no concern for your project. Yes, it would have originally had an electrolock but that appears to be long gone. The very early units did attach to he distributor I believe. I have no experience with the early units but, if my memory is serving me correctly, that was the case. By 1939 they went from the switch to the coil.

Ok folks, this is all great info. I really appreciate all the help thus far. I'm trying to maintain some form of "period like" but I think ill go with the plain key switch. I'm going to try to make it to a locksmith in town this week to see if they can remove the existing cylinder and hopefully the switch itself is still "power passing".

The 53 will have a "regular" coil. Just hooks up with a few wires. Regular On OFF or ON Off ACC ignition switch. No problem.
The only electrical gauges you have are the fuel gauge and Ammeter. You just reverse wires/cables here and there on a few components for Neg ground. Both gauges are useable in either neg or pos ground. 6V.

https://americanclassic.com/chevy-g...n-switch-universal-foot-start-sku-53-440

We need to see the old switch to see if original and what the bezel nut looks like so we can advise which NEW switch will look OK. I advise a new switch/cylinder. Don't know what is gained with a locksmith and using an old tired switch?
You may be able to use the old bezel nut on new switch if that's all you see out front of dash. I'm not sure how your old switch mounts. Dash pic will help also.

PIX PIX PIX!!!!!!!!!!!!!!!

We will help you wire the whole truck when ready. It's not complicated. If you are not experienced, Don't start buying stuff until you check with us.

What level are you after? Show truck, super original in every way? Daily, safe, reliable driver? resto mod?

Ill attach the best photo I have today. The switch is currently at work in a 5 gallon bucket of parts I was cleaning up. Ill also attach a photo of what the dash would look like assembled.

Ultimate goal is a weekend driver with period like mechanicals. I have a project journal going if you'd like to check that out. I only recently picked up the 248 (last week) so I haven't updated it yet.

I'll get some better photos of my existing switch tomorrow.

Wow Daniel, just looked at the journal. Didn't know you were an advanced restorer/refurbisher. You are way past journeyman level even. Nice work and thorough. I don't need any more pics, I see you know what you are doing. Just a suggestion here and there. Keep up the good work. That is a truck that is worth the effort.

The 4-digit key code should be located on the lower portion of the door handle body. So, if your locking door handle is still in place on the truck and you can remove it, even if the lock cylinder is missing, you should be able to see the key code and order a replacement key. If your truck has the original ignition switch and door handle, the ignition, glove box lock, and door handle should all be keyed the same. It may be a long shot but worth a try. If you do a search on eBay, you can find some 1939 GMC/Chevy locking door handles for sale and a few have pics that show the location of the key code.

My ‘39 Chevy was still set up with an electrolock but I wanted to switch it over to a newer coil setup. Because I had the original key, I was able to remove the ignition switch from the electrolock ignition switch body and purchase a vintage, but newer, 3-post Delco 1116507 ignition switch body that my ‘39 ignition switch fit into and that accepted the original ‘39 bezel. Looks identical on the dash and works great! I’m not sure if the 1116507 configuration is compatible with your GMC’s original ignition but it worked on my Chevy. Good luck!

Bart, I feel generally capable but I don't have anybody locally to bug with all my questions. None of my friends or family are into this stuff. I'm just 33 so I'm having to learn all this old stuff from scratch. Long story short is that lack of knowledge and experience with this older stuff is my biggest challenge.

Here's what we're currently working with. I found a couple on eBay that visually look similar. I guess I'm just stuck deciding if I should get a 2 terminal switch like this one or go to a 3 etc.

In my head, a two makes sense since that's what was in it and I'm sticking with the same engine family and accessories but would a third terminal be useful?

Daniel - A question on your possible 3 terminal switch options. Can you tell if they are for a momentary starter position (only use would be for switching to a non-foot operated solenoid engaged starter) where the switch springs back to the on/run position, OR is the 3rd terminal for an accessory load control (switch stays in the 3rd position allowing accessories operation but not engine start/run)???

I think I see you are not looking at the type Dan is speaking of. Which has a position that has a momentary spring loaded position for non foot/solenoid start. I think you are looking at two position, two terminal and three terminal older ignition switches. It really really really makes no difference which you get of those.
The 39 and 53 are wired the same. Foot start. 6V

1. Switches are designated by positions and by number of terminals. (and operation, I.E. rotary, lever/toggle, slide, push button, etc)
2. A two terminal, two position older switch is just OFF position and ON position.
3. At some point a three terminal, two position and a three terminal, three position came along.
4. The three terminal, two position is... ALL OFF and ALL ON.
5. The three terminal, three position is OFF-ALL ON-ACC ONLY

In simple original wiring, you will be wiring either type with one wire from the ammeter to an IGN sw terminal. Then two wires from another ignition switch terminal to the gas gauge and to the coil. The ACC or a third terminal will not be used and no one will know but you.

You are in the right place here, the membership pool knows everything you will ever want to know about your 39/53 and glad to help with any question.

Just remember, you are showing OLD switches which can be worn/internally broken or corroded or both and they don't look like they are very easily torn apart to clean, but can be done. They would need a continuity test and voltage test if they are pricey. If cheap, take a chance I guess. Some of that stuff does not last 86 years. Trying to use preowned/NOS switches, tumblers and old/dual use key may be driving you too hard unnecessarily. The "O" in NOS stands for "OLD".

If you open an old one up that does not have a key, you may be able to release the tumbler form the "back side".