Bought a supposedly "stock replacement" ignition switch. 3 pole, putting it on a 12 volt system with a 350 auto 53 GMC. None of the poles are marked as to what goes where. Anyone have a clue? Thanks.
Look for an original wiring dia. If your GMC had a floor starter. This switch will be more difficult to wire. Your 350 probably uses a stock starter. You will need a later model switch. Like a tri five car
One terminal is for 12v power from the fuse box. The other two terminals supply power to the ignition, and switched accessories (gauges, radio, etc.) To check which terminal is the 12v battery power, use an ohm meter to check which of the other 2 terminals do not have continuity with the key in off position. You are going to need a push button to engage the starter if you use this type switch. Your truck originally had a foot switch to start the engine.
You looked really close at the black piece for hard to see, molded in letters? and did you check that it has a "start" position, or not? buy turning the key, see if it springs back when you turn it all the way clockwise
I think he has the same style switch that is used in 49-52 chevy cars. It has a lock position (key turned to the left) Off position (key straight up/down) and On position (key turned to the right) Switch doesn't have a start position that springs back to the on position. The only difference between the car and truck application was the trucks had a foot switch beside gas pedal to engage the starter. Cars had a push button on the dash.
Remember that GMCs are not Chevys...they usually had better features. But it sure could be a switch for a Chevy, since GMC parts are not usually reproduced
Here is a HAMB from 2020 that should answer your question..... Technical - 1954 Chevy ignition switch | The H.A.M.B. (jalopyjournal.com)
Unless you buy the switch from Chevs of the 40's you will have to run a push button starter switch. The first Key start GM trucks were 55 Chevy 'V8 trucks. Six cylinder trucks had stomp start up though 59. Those universal switches from the parts house just wallow out the hole in the dash when they get loose an they get loose all the time. Note that GMC was positive ground up to 55 when they went to 12 volt. That means if you use the stock gauges you will need to reverse the wires on the ammeter. You can put the starter button any where you want but my preference is under the dash where I can easily reach it but it is out of sight from casual observers I lost my key for my 48 one time in Texas and drove it for a year with a toggle switch and pushbutton under the dash.
I am going by the pictures in the original posting by Casper50. It is the same switch in my 50 coupe. GMC's used the same ignition switch as the Chevy trucks. What most people end up having to do if they upgrade the wiring and engine in the 47-59 GM trucks is either install a more modern switch in the dash with a starter motor position on the switch, or they upgrade the steering column that has an ignition switch. If Casper50 uses the switch in the pictures, he will need a push button or toggle switch to start the engine. It is basically a battery cut off switch that uses a key.
The Jalopy Journal
