I am bypassing my key ignition in favor of toggle switches. One to start, one to switch "ON" and one for accessories. My question is, what is the difference between the "ON" and "ACC" positions? Is there a reason to seperate the two? BTW, this is a 61 F100. Pretty basic truck. Thanks

 

In ACC position, there is no voltage to the coil +. This keeps from overheating the coil and burning up the points when you are playing the radio and such.

You may also need a double pole switch for the ignition. I am not sure about a Ford, but I do know a GM alternator will feed back voltage to the coil + and keep the engine running with the key off, if the alt feed and the coil feed are on the same circuit.

 

Thank you. Makes sense and good idea about using a double throw switch. Hadn't even thought of that.

 

Just to keep things straight, there is a double throw type switch, and there is also a double pole type switch. And you can actually have a double pole, double throw switch.

A Single pole-double throw would be a switch with 3 terminals on it. The center terminal is common, and putting the switch in either position will connect the center common to either outer most terminal. This would be useful for high/low speed. If you had the "center off" style of double throw switch, you could use it for up-off-down, or left-off-right type applications.

A single pole-single throw will have two terminals. One direction connects the two terminals, the other direction disconnects the two terminals. This is useful for on-off applications. You can buy a special "spring return" type and use it as the starter switch.

What I was talking about was double pole. A double pole-single throw switch would have four terminals. It works like a singlepole-single throw, but has two seperate sides to the switch(this is the one that would work for your ignition switch).

A double pole-double throw switch would have six terminals.