1951 Ignition switch wiring question

[Donaldo]

My '51 truck has the original ignition switch in working condition, even have keys, just no wires

It is a 2 position switch and has 3 connections on the back, none have any markings. I've searched the list, looked thru the Assembly and Shop manuals without finding any 'it's clear to me' information. I will be using a start button in the circuit between the starter solenoid and the key.

Would someone please explain how this 3 post ignition key is supposed to be wired ?

[octanejunkie]

I don't have your year or type of switch but perhaps this will help

This 51 Truck diagram linked shows a 3-terminal switch but the terminals aren't marked (of course)
http://chevy.oldcarmanualproject.com...51ctsm1203.jpg Looks like one terminal is unused in that diagram.

Basically, the switch will be wired in between the battery and the rest of the truck's circuits, with the pushbutton triggering the starter.

Something like this, replace the rocker switch in the diagram with your keyed switch


If the posts on the switch are not marked at all, and don't match any printed material you have access to, you can test/verify the connections these on a bench using a DC power supply, a pushbutton switch and 2 small light bulbs. Re-create your switch circuit via trial and error and figure out which posts on the switch are which.

Someone with the same switch will be along soon to give better advice, I'm sure.

[mr48chev]

Here: You can expand the pfd to read it easier. I'd save it to my computer for reference.
http://chevy.oldcarmanualproject.com...df/51truck.pdf

You have to track the wires to the other ends. One goes to the coil and one goes to the regulator Bat post.
If a guy had the priinter to do it that can be expanded out to 1000% or ten times to where it would be wall poster size.

I found it on this page http://chevy.oldcarmanualproject.com/electrical/wiring/

[Donaldo]

""Here: You can expand the pfd to read it easier. I'd save it to my computer for reference.""

Thank you. Saved it and printed it out -
In testing the switch it doesn't seem to matter which pole is powered, with the key Off the other 2 are both cold, with the key On they are hot - in either of the 3 configurations.

[mr48chev]

I'm kind of thinking that the second (hot when on) post may be for the gauges.

I've never had my nose under either of the dashes of the two 51 cabs I have to tell and the original switch was long gone in my 48 in 1973 when I bought it.

[octanejunkie]

Originally Posted by Donaldo

""Here: You can expand the pfd to read it easier. I'd save it to my computer for reference.""

Thank you. Saved it and printed it out -
In testing the switch it doesn't seem to matter which pole is powered, with the key Off the other 2 are both cold, with the key On they are hot - in either of the 3 configurations.

Ironically, both links posted for the OP contained the same wiring diagram from the same site. How he chooses to wire his switch/truck is now his option since he tested his switch (as suggested) and knows what that the terminals do.

I would caution the OP against running excessive amperage through a vingage switch and consider integrating a relay into the circuit(s) coming off the switch should he deviate from the stock wiring and accessories and load.

[Donaldo]

""I would caution the OP against running excessive amperage through a vingage switch and consider integrating a relay into the circuit(s) coming off the switch should he deviate from the stock wiring and accessories and load.""

Thanks for the input - it's now a 12v system, which I understand is of lower amps than the original 6v system. I am planning on using relays to several of the systems we are going to be using.