Hey guys, first post so please be gentle. I apologize in advance for this post because I assure you I know how to use the search button. I have read multiple threads and watched quite a few videos and I am frustratingly, still confused. Understand that when it comes to wiring, the term novice is giving me more credit than I deserve. I have a 2012 F250, I would like to add three led strips in the bed (two in bed, one in tool box) and a led light bar for when I am plowing. Now, what I think I understand is that the pass through wires are there merely for the convenience of you not having to run anything through the firewall (one wire, dead end to dead end, no splice anywhere). What I am having trouble with is what to wire to what, obviously, I have one red wire and one black wire from my accessory. My first question is at any time do I need to run a wire to the battery for power or do the aux wires near the pass thru wires under the drivers dash already have power? If that is the case would I just run the red wire of whatever accessory to the according aux wire and then ground the black somewhere? (Where?) Surely, I don't need to make a run to the battery then to the pass thru wires in the engine bay and then connect the pass thru to the aux wire? I feel like I am making this more difficult than it needs to be but I really do not have any wiring experience. I've looked at the wiring diagram from Ford and I don't understand, I am a dummy. I don't want to pay someone to do it, I'd like to learn to do it myself.

Also, my led light bar is going to be purely for functionality and I do not want to drill for the mounts. I am going to use magnet mounts so I can take it off whenever I'd like. Having said that I was wondering if anyone had any suggestions on connectors or if this is even possible but once I figure out the wiring I'd like to run the according wiring from the upfitter switch under dash, up the passenger a-pillar, and terminate it near the headliner with a connector of some sort. Something durable and easy to connect and disconnect.

Thank you!

 

Most of it depends on the amp draw of the accessory you are wiring up.

Something that is high current draw, you would want to use the smallest amp rated upfitter switch to control a 30 amp relay. The accessory would be across the normally open contacts of the relay with an inline fuse in the red wire for the accessory. The other two contacts of the relay would have have the wire coming from the upfitter and a ground to energize the relay. The upfitter switch would control this relay.

If the accessory is lower amperage and can be tied to an up fitter switch that might be rated at 30 amps, then you can wire it directly to the output of the upfitter relay box wires. The accessory can be parallel or series with others as long aw the amp rating is less than the upfitter switch amp rating.. The output would go to one side of the accessory(s) and the other side(s) would be grounded.