I'm installing a pair of tractor style work lights on my rear bumper and want to wire them so they come on automatically when I go in reverse but also want to be able to turn them on on demand.

I'll be using a relay and tapping the reverse light to hook up to #86 on the relay to trigger the relay to turn on. I also want to put an independent switch hooked up there to turn them when ever I need light.

My question is, how to wire up the switch so I don't back feed the reverse lights and damage the factory circuit?

 

Simply use two relays with battery power tied in parallel through the two relays. So your two relay triggers (back up lamp, and toggle switch) will be independent circuits, but the battery to work light circuit will be a single circuit that can go through either relay.

 

What about a diode?

 

how about a 3way switch

 

I considered to relays but wasn't sure how to wire them together. A friend also mentioned a diode, although I don't have any experience with them I think I understand how the protect the factory circuit.

The schematic on the 3-way switch looks pretty simple. Based on what you've shown me I'm going to go that route. I'll post some pics once it's done.

Thanks for the replies!

 

yes, a rectifier diode would be really simply also. it will only allow power to travel one way. just make sure you get the right amp size. dont get one to small or you'll backfeed and it will heat up to much. make sure you dont put the diode anywhere where it will catch things on fire, cause they can heat up alot when exposed to electricity for a while.