Reverse light wiring into additional led help

I removed my reverse light as it was about as bright as a candle and I've attempted to wire it into an existing relay that powers my two led work lights on the rear. I brought a 3 way switch so I could have it either totally off, on by switch and what I was hoping was on by reverse switch. Wired it all together and it blew the fuse. Tried a new fuse. Same again.... Got the multimeter on the cable from the reverse switch? And it was sat at about 12V but went to 0 when I put it in reverse.. This Is with the truck ignition off... How do I get around this?

The reverse switch just switches the two wires connected to it together. It sounds like you have a full earth on the one that normally goes to the light unit. Check your connections.

I'll check the connections maybe I made a mistake somewhere as I've doubled them into the wires that go to the relay. So my reverse cable should have 0V until I put it into reverse?

Could it be that I've put a 12V feed from the battery to the I put of the fuse and I've also put the reverse wire to the switch Input also. So basically I've got 12V flowing the wrong way to the switch and then when 12V comes from the switch when I engage reverse it cancels it out to 0V just like what happens with an alternator warning light....

Question is how do I use an on off on switch to light up my reverse light, I want to be able to either have it on the reverse switch. Off all together or on when I switch it on...

This circuit will do what you want. What it does is add a bypass to the original switch, which will turn the reverse light on regardless of the gear selected. The on-off-on switches between either the original gearbox-switched supply, and the new constant supply. In the middle it is off.


Remember that for any manually-switched reverse light to be legal (this counts) you need some sort of tell-tale to alert you that the reverse light is switched on. The simplest way would be with an illuminating switch- wire the LED between the reverse light output and ground.

In your case of using work lights with a relay, the connection I've marked as 'to reverse light(s)' will go to the trigger on the relay.