How do you wire a on-off-on switch to run from the battery or the key on acc fuse?

[Steel City 06]

Do you mean you want the ability to turn it on regardless of key position?

If so simply switch the fuse tap to a fuse that is permanently on.


Unless you're talking about an independent switch to activate the switch pod when the key is off. Or basically all switches become active when a key is in the ignition or a separate master switch is on.

If you want to do that, the easiest way would be to tap into the turn-on wire with a diode (like the ones used for trailer wiring). The one ended (cathode) side goes to the switch panel, the 1st upstream (anode) side goes to the ACC trigger wire you already have, and the 2nd anode goes to a switch and then to a permanently on 12V source.

In that case the fuse panel would become active if the key is in the ignition and turned, or the switch is turned on, or both. You need the diode to prevent backfeeding the ignition source.

I'm assuming there is already an internal relay for the lights or any other fuse panel accessories. You wouldn't want to tap any significant power out of an existing accessory wire.

This is the type of diode I am referring to:

 

[Steel City 06]

Alternatively you can use a SPDT switch to separate the wires. The ignition input goes to the top prong, the 12V constant goes to the bottom prong, and the middle prong becomes the output which goes to the switch panel.

This would be cleaner and no diode would be required. Ideally you would want a SPDT switch that has a ON-OFF-ON function.

Here is a good example of a basic SPDT switch:
https://www.waytekwire.com/item/47691/Snap-In-Round-Rocker-Switch-47691-/
Now that I think about it I'm pretty sure this is what you are talking about.

 

[Wingback73]

This certainly works, but requires an extra switch beyond the SPDT/DPDT method (need to both turn on the panel and then be able to turn on the switch itself), and if I'm following. I have 4 lights, as an example, front, left/right a-pillar, and rear. I want each of those to either be able to be off, on, or triggered. In this case, "triggered" means high beams for the ones pointing forward and the reverse lights for the one in the rear. I probably could have done that using diodes, but SPDT (on-off-on) switches are a lot easier.

All 4 of them have an input wired to a constant power, the second input wired to the appropriate trigger wire, and the output goes to the relay to control the lights themselves.

Not saying this is better since I think each serves a purpose - just sharing.

d-