The Stovebolt Site Forums The Shop Area The Electrical Bay 1953 GMC 1/2 ton ignition switch confusion

Hello everyone. I am in the process of getting my 53 back on the road. I'm having some issues with the new ignition switch I ordered. The truck had no keys when I got it and someone had added a push button start. Now I've switched it back to the foot start and "hot wired" it to run but now I'm trying to add in the key back into the mix. Truck is also 12v

So what I've got is what I think is the correct ignition switch. It was not labeled but looking at the old one and from other info I've read the battery post is the one in the middle and will be pointing towards the floor. Hooked that up and took my volt meter to the other post and with the key straight up and down I've got 12v to both the coil and accessory position. With the key turned counter clockwise (11 o'clock) I've got 0v at the coil and accessory position, and with the key turned clock wise (1 o'clock) I've also got 0v again at the coil and accessory position. Is this correct? I thought 11 o'clock was power to accessories, 12 o'clock was off, and 1 o'clock was power to coil and accessories.The way it is now it's OFF ON OFF.

So it's a 1953 12v with foot stomp start and has a 270 motor if that makes a difference. Here's the link to the switch I bought
http://www.classicpartsusa.com/prod...Ulrfv4gIVDVYMCh2PagX3EAQYAiABEgLcqfD_BwE

Thanks for the help

I have an original 1954 switch. It has only 2 positions: on/off. There are three terminals on the switch, but only 2 were used. So, I expect that since you have a reproduction with 3 positions on the switch, the terminals are different from the original. IOW, don't be surprised if the "middle" terminal is not BAT.

I would sit down with your new switch and your VOM set to ohms and try all the combinations of connections until you find the one that works.

Well I took the switch out and ohm'd it and I'm seeing the the exact same thing I was seeing when I checked it hooker up with power. Now I have a machinist background, not an electrical one. Maybe there is a check im doing wrong or maybe one of you guys has a better way to check.

Thanks

Try again.

Put the switch in the middle position (normally off) and check for continuity between all pairs of terminals (1 - 2, 2 - 3, and 1 - 3). If that's truly off, you should have no continuity at all. (maybe between coil and accessory).

Then try the 11 o'clock (assuming that's the "standard" accessory position), and do the same. In that your should have continuity between only one pair of terminals. One of those will be battery and the other accessory.

Then in the 1 o'clock ("standard" run position) check again. You should have continuity between all three contacts, battery, coil and accessory.

You might want to hook it up on the bench and try every combination of wiring. You should be able to determine where they go.

Or do the tests above and make a table of which are connected in each key position and post it up here. Someone should be able to figure it out for you.

Does that switch have a small handle that hangs down below the key slot? If so, the 12:00 position is the "ignition on" position. Turn the cylinder to the left and remove the key, and you've got "off and locked". Re-insert the key, turn the cylinder fully clockwise and remove the key. That's "off and unlocked". You can use the tab to turn the cylinder to the middle position and start the vehicle without a key. Some commercial trucks, school buses, and such had that optional switch setup so the vehicle could be operated without the need for a key. The 1958 Chevy school bus that I rode for 3 years in middle Tennessee back in the early 1960's had exactly the same switch.
Jerry

I'll try again tomorrow. I already installed the switch early this afternoon noon. Before I installed it I did a continuity check on the new switch in the same pairs as described and I got the same as before. It has to just be the way this switch is. I did a continuity check on the old switch and everything work how it was supposed to, 11 o'clock has continuity between battery and accessory, 12 o'clock had no continuity between any of the terminals, and 1 o'clock had continuity between all the terminals.

Guess I'll be looking into another switch down the road. This one will work and serve its purpose for now.

Thanks everyone

My 51 Chevy 2dr sdn operates exactly as described by Hotrod Lincoln

There is no accessory switch position in any of these switches.
Check attached photos

Factory Set-up for 49-53 ignition switch, Two position ON - OFF
11:00 o'clock position OFF
.1:00 o'clock position ON

There are three terminals.
A. One terminal feeds voltage to the switch.
B, C. terminals receive voltage when the key is switched ON
B and C are internally tied together..

That said, if you feed voltage to the switch by connecting to B. C will also receive voltage and vice versa.
But the key ON position will become OFF and OFF will become ON . The ignition will be reversed..
And you will only have one switched terminal with voltage instead of two.

GM film strip,Three Position ignition Switch

Ignition Switch Changes Jim Carter tech article.
The Jim Carter article differs from the film strip. Third paragraph. Reason why may be on how the switch is wired.

Three position switch The one Hotrod Lincoln was talking about. 1950 GMC . 1:00 o'clock position OFF UNLOCKED

Two position switch 11:00 o'clock position OFF

There is a possibility that you may have a three position switch housing with a non-teardrop lever key cylinder.

The thing is, both type of switches work essentially the same ON - OFF, The only difference is, the teardrop lever switch has a OFF LOCKED position
11:00 o'clock position OFF LOCKED
12:00 o'clock position ON IGNITION
.1:00 o'clock position OFF UNLOCKED

47-48 Ignition switches THREAD for more info.

xfiles

Thank y'all all for the responses. I've checked the switch again I am still getting the same results. My switch does not have the little lever at the bottom. It is a 3 position and works as OFF ON OFF. Right now I'm just going to leave the switch as it will work just fine for now. I still have a long ways to go to get this old girl road worthy.

Thanks again