The Stovebolt Site Forums The Shop Area The Electrical Bay Ignition Switch Terminal Identification

I've seen this question asked several times, but have not seen a definitive answer yet. I burned up a wiring harness, just paid a lot of money for a braided original type one, and I want to make sure I get it right this time.

I have a '48 half ton. There are three terminals on tha back of the switch, and none of them are labeled. One is at the six o'clock position, One is at the two o'clock position, and let's call it the 'DS' or "driver's side" terminal, with the third being at the 10 o'clock, or 'PS' or "passenger's side" position.

The directions from YNZ say to connect wires 19 and 22 to the "Ign" terminal, and wire 18 to the "B" or "Batt" terminal.

Since noe of the terminals are marked, can anyone definitively tell me which terminal is "Ign", which is "Batt", and what the third terminal is used for?

A wiring diagram doesn't help. They YNZ people can't help. I'm guessing the terminal ot the bottom, or 6 o'clock position is the hot wire "Batt", but I'm not certain.

:confused: :confused: :confused:

Tom R,

I'll give you my take on this, but it will require a meter to confirm continuity.

The BATT terminal will have continuity with the IGN terminal when the key is switched one position clockwise from center...as is, 'turn on the key'.

The BATT terminal will have continuity with the ACC (the other) terminal when the key is switched one position counter clockwise from center.

With the key switch centered, there will be no continuity to any other post, and no continuity between the IGN and ACC posts.

Lots of words, but it's actually quite simple to see if you have a meter.

This is for the stock 'stomp starter' right!

Stuart

Tom R,

I might be semi-wet on the above description. It appears there could be continuity between BATT and ACC when the key switch is turned to IGN, which is one position clockwise from center.

When in the ACC position, which would be one click counter clockwise from center, you should have continuity between BATT and ACC, but not IGN.

I'm sure I have confused you completely now.

Stuart

Here's another question..... My key switch only turns one way. I think it's original, so what's the deal with that? (49 3600) Is my switch bad? I also have just hooked up a YnZ harness. I don't really see how the ignition switch could burn up the wiring... all it does is "connect the wires" when you turn the key.

atomarc, I don't believe I have an accessories position. There are three switch positions - "off/locked" (key turned to full counter clockwise position and removed); "on" (switch in vertical position); and "off/unlocked" (switch turned to full clockwise position).

oldcarandtrucknut, you have the same switch I do. You need to have the key in the ignition switch to turn the switch to the "off/locked" position I described above. If you have the key fully inserted into the ignition switch and you can only turn it to one direction from vertical, then I'd suspect you have a bad switch.

You're right, of course, about the switch not burning up the wiring. I had other issues (see my other post about "An idiot with a smoking problem"), but it didn't happen until we left the switch in the "on" position, and I want to make sure that I wire it correctly so I don't have current when the switch is "off. "

Tom R,

Interesting. I guess my question would be the same as your question...what is the third terminal for. With a meter, you could map the terminals which might give you a clue as to the intent of the switch.

I have heard the famous story about farmers being able to turn the key on, remove it, and have the ability to jump in and start the rig sans key!

This doesn't make too much sense to me, plus it seems like the coil/points would be short lived.

My guess is that "off/unlocked" is the equivalent to today's ACC position.

Stuart

You're right on about being able to jump in and start it without the key, but that doesn't mean it's "on" all the time. There's that "off/unlocked" position that saves the points.

Tom R,

If you could jump in and start it without the key, I would think that meant it was 'on' all the time. If it isn't ON, then it must be OFF! If it is OFF, will it start??

Wouldn't it make more sense to think the third terminal on the switch was the key "off/unlocked" function to allow Mr.Farmer to play the radio without the ignition on, as he waited for Ms.Farmer to get her nails done!

Stuart

On my stock switch in the forty-six, here's what I've got:

Center, top
Armored cable going to the coil.

Driver's side
"Batt" terminal from Ammeter

Passenger's side
"Acc" terminal for devices (turn signal, tachometer, and dash fan are currently hooked here on my truck)

This is the old school stock "two position" (on and off) switch for use with a foot stomper starter.

Might the middle terminal be an independent hookup for the coil wire?

I like Stuart's suggestion of a continuity check. That'll tell you a lot.

atomarc, two of the three switch positions will work with they key out. Vertical is "on" and that's where the switch has to be when you stomp the starter button.

Key turned counter clockwise is "off/unlocked" There's no current going through the switch, but all you have to do is turn the switch to the vertical position (there's a handle of sorts on the bottom of the switch to do this.

Brendan, mine doesn't have that armored cable yours does. Nor does it have a terminal at the 12:00 position like yours,

The third position is with they key turned clockwise from vertical ("off/locked"). When you do this and remove the key, the switch can't be turned to the "on" position. My father is trying a continuity check with a 6V battery and a light bulb. I haven't heard the results yet.

Tom R,

The fog is starting to clear in my brain. I didn't understand how Mr. Farmer could hop in and turn the key from the 'unlocked' position to the vertical 'on' position....a little handle!

Ask your wife to get you a Volt/Ohm Meter for Columbus Day...it's nice to have a helper/DAD.

Stuart

Okay, I have the results. The six o'clock position wire is the "B" or Battery wire connector, the driver's side (10 o'clock position) terminal is the "I" or Ignition connection, and the passenger side (2 o'clock position) terminal is dead. Why the third connection is dead is beyond me. Perhaps I have a bad switch, or maybe it's designed that way, although I can't imagine they'd put it there and have a connector screw and washer on it for no reason. In any case, the wiring diagram shows only two wires going to the switch.

Since the switch appear to be only a simple on/off switch, I don't imagine it makes a difference which way it's wired, as long as one doesn't use the dead connection.

So, the switch is wired, we turned it on briefly, and no smoke escaped from the wires. I didn't connect the wires to the distributer and the coil yet, though, so who knows what'll happen then?!

Oldcarandtrucknut, which way did you wire your switch?

Tom R,

Good for DAD and his little light bulb. As you mentioned, all the wiring diagrams show only two wires, and the key switch functioning as a ON/OFF switch..........but I sure wonder what that third terminal is for.

I can't believe it is dead. I would guess there is continuity in some configuration your father might not have tested.

Would they have hard wired a dealer installed radio in 1948 so it could be turned on without a turn of the key. Maybe that extra terminal is a prehistoric ACC position for a radio or foot warmer!

Who knows!

Stuart

Tom, that is also how i wired my switch. I tested it with an Ohm meter and it showed correct, however it also turned on the extra terminal. I have not hooked up the battery yet, so not 100% sure about it being correct, but I am 99.5% sure it is.

I just wired my radio in recently. So to confuse everyone this is what I found on my 1954 chevy 3100.
I tested the three positions on my ignition. With the key in the off position (center). One had power that was the one coming from the ammeter. The other two had no power made sense to me.
With the igntion on (Right)everything had power all three posts that made sense to. With the ignition turned to the left Only 2 posts had power the original from the ammeter and one of the other post. I asummed this postion is for accecesories this is the post I put my radio to My radio works with the key turned on to the right and left. I think its pretty simple.... my heater also works off the same terminal as the radio.

petmil - i have a 54 and it is wired as yours with the exception I don't have a radio but my heater is wired to that third terminal.

petmil - i have a 54 and it is wired as yours with the exception I don't have a radio but my heater is wired to that third terminal.