I've scanned the threads for ignition wiring on my '56 F500 and found two diagrams that are similar but not exact.

The left image has the starter solenoid "I" terminal to Coil "+" terminal. The right image has the starter solenoid "I" terminal to Ignition."

The left image has the voltage going into the starter solenoid "I" terminal affected by the ballast while the right image has the voltage going into the starter solenoid "I" terminal unaffected by the ballast.

Which is correct?

 

I have trouble with electrical pictorials even though I have a lifetime experience with electronic circuits and relay logic. I can not see where either is correct. You want a hot non dropped +12v to the coil during periods when the starter us engaged. Once the engine has started, you want that full 12V+ to drop to the run or dropped voltage through the run or ballast resistor. Perhaps I am missing something. Does your truck have a separate starter button or is start through the twist to start ignition switch?
Edit: Looking at the circuit again, on the left circuit, is that a ghost line between the ignition and coil +? If so, that is probably correct.

 

The one on the left is correct (as far as the "I" terminal anyway). All of the ones on the right are wrong in that regard.

 

Hi CC and Happy New Year.

The images are a little small and it's a little hard to make out, but if you are running stock ignition with points, I believe the left is correct. There should be a direct connection between the starter solenoid/relay "I" terminal and the the coil + terminal. Attached to that connection is one side of the ballast resistor. The other side of the resistor goes to the ignition switch "I" or coil terminal. Here's how this set up works. When you are cranking the engine, the starter relay to coil connection provides a full 12 volts to the coil for cold cranking hotter spark. When the engine starts, and you let off the key, that full 12 volts connection is broken, but then the coil gets ignition voltage thru the ballast resistor and ignition switch to keep the engine running. They say all the ballast resistor really does is protect the points and coil from getting too hot, melting down, and running down the battery if the ignition switch is in "run" and the engine is not running. Others say it's there because you don't really need full coil voltage if the engine is running is it helps maintain ignition voltage. Either way makes sense I guess. If you are running aftermarket ignition such as Pertronix, the manufacturer many times instruct you to take the resistor out. Hope that helps!

 

Wow. Thank you everyone. All sorts of good information here.

So, when I got the truck the starter button was the horn button. I know...a big LOL there, right? It gave me a chuckle for sure.

The ignition switch was wired so you'd turn it all the way until you felt resistance and at that point the starter fired, the truck started, and the ignition switch sprung back to ON when you let go of the key. No different than modern vehicles.

I'm just confused by the drawings because it shows two different paths for the coil and ballast.

On the left drawing the ballast and the line from the starter relay "I" terminal share the coil "+" terminal.

On the right the ballast and the line from the starter relay "I" terminal share the "Ignition" terminal at the starter switch.

Both of these drawings came from the FTE forums and seem to reflect the same vehicle, voltage system and year. But I understand how the coil is supposed to receive more voltage when the truck fires and then it drops back down (via ballast) while running...I'm just trying to figure out current direction and paths.

So the vote is the left is correct (or this post, the bottom image above here) re: ballast and the line from the starter relay "I" terminal share the coil "+" terminal?

Here are the images non-compressed.

 

Yes, the one one the left is the correct one, showing the ballast and the line from the starter relay "I" terminal sharing the coil "+" terminal. The ones on the right are incorrect, because the ballast resistor would be in line during cranking. That my vote. I double checked this looking at the 56 shop manual.

 

Can you point me to the thread where you got the wrong ones? I'm guessing they are "JuliesCoolF-1" pictures, there were many wrong schematics posted by that user.

 

Thank you all again very kindly for your assistance. I don't want to blow anything up.

Should I want to use a starter button, I would imagine I'd simply have to put the button between the ignition switch (I believe it is currently on the "S" terminal) and the "S" terminal on the starter solenoid - which would only allow power when I turn the key to "Start" fully and hold it there while I press the button. Correct?

The thread that I found the wiring info was here: https://www.ford-trucks.com/forums/8...itch-help.html

 

Yes sir. You could do that and it would work. If you hide the added "start" button it would make a good anti - theft feature. Or you could eliminate the key twist start completely by just running one side of the start button to the " I "or coil terminal on the ignition switch and the other side of the start button to "S" terminal on the ignition switch. This way you are by - passing the twist to start contacts on the ignition switch. And if you still want to simply twist to start....you still could. If you desire no twist to start at all, simply disconnect the wire from the "S" terminal on the ignition switch and connect that wire to the switch side of your start button. The other side of the start button remains connected to the ignition switch "I" terminal.

 

Ok got it! But just so we're clear, above you say I can eliminate the key twist start by wiring my start button between the "I" and "S" terminal on the ignition switch. But by doing so I don't see any wire hook up to the "S" terminal on the starter relay. Unless you meant the "S" terminal on the starter relay rather than ignition switch.

I think I'm doing the switch between the "S" terminal on the ignition switch and the "S" terminal on the starter relay and hide the switch.

Thank you very much for all your help gentlemen!

 

Hi Cal,

What you would be doing is leaving your ignition switch, and starter relay wired as they already are, and simply adding a push button to the ignition switch wiring:

If you want to twist the key, and then push a secret start button, simply disconnect the wire that is connected to the "S" terminal on the ignition switch, wire that end to one side of a push button, (the other end of that wire you just removed still feeds the "S" terminal on start relay) now take the other connection of the start push button and wire it to the "S" terminal on the ignition switch. What you have now done is simply place a push button in series with the start contacts in the ignition switch. You can twist the ignition key, but no current flows to the start relay until you hold the key to start and then push the button. Better yet, just look at that last large, schematic that Ray,Ross and I say is the correct one. See the start button? It's the same thing, but now you are getting the 12 volt power from the "S" terminal on the ignition switch and feeding it to your start button.


Hope this helps!

 

I just had one of those AH-HA moments. I see it clearly. Very detailed response. I'm going to wire it up!

 

Yep you should good to go. If you have any more questions please let us know!