Wiring AUX reverse lights

I'm installing aux reverse LED lights to a 2014 F-250 and would like them to turn on in 1 of two ways: 1. slave off the reverse light circuit when in reverse 2. use an AUX SPST switch to turn on the lights anytime Is there a single relay that can be used to accomplish this? I would like to avoid backfeeding to either circuit as the AUX switch is factory installed and i'm not sure if it will burn up anything in the switch or controller (if Ford ran the switch output through the fuse panel or ecm). I know diodes are an option, but would the voltage drop caused by the diode be detrimental to the lights or affect brightness? The pair of lights will draw 3amp total. thanks for the help!! Matt

A standard 30A relay should be fine. Be sure to fuse the main lead for the relay. For triggers, insert a diode from the relay to the reverse wire circuit then add what ever you are going to use to trigger the lights. Should be good.

Thanks! Is a diode needed between the relay and the switch? Or will the switch be able to handle that?

A couple of ideas: It sounds like you have the "upfitter switches" in your Super Duty. You want to use one of these for the aux Back Up LED's. If the LED are only 3 amp total, use (2) 5amp diodes, no relay. At the rear of the truck, the factory back up lights should be blk/pnk. Tap this wire, put a 5 amp diode in this wire to the aux lights, band towards the aux lights. Run a wire from your upfitter switch to the rear, put another 5 amp diode in it band towards the aux lights. Viola. Done. Minimum parts, minimum hassle. And everything is protected by factory fuses.