Reverse Signal Wire

[borahshadow]

So I'm installing some driving lights tucked up under my rear bumper so that I can see down my lane when I am backing down it at night. I need to find a wire that goes hot (or ground) when the truck is put into reverse so that I can trigger the relay that will turn on the lights. I found a green wire going into (or out of) the transmission that according to the wiring diagram I was looking at should be a reverse signal wire.

I was wondering if anybody knew how that wire worked...
What does the factory use it for? I would assume it doesn't actually switch the transmission into reverse since I thought that was mechanical...
Does it go hot or ground?
Would I have a problem putting an additional (albeit small) load on the wire?
What would happen if this wire accidentally grounded? (always something to think about with modifications... no matter how careful the wire is routed)

 

[Mike]

Reverse is the thick green wire at the tail lights, there should be an extra one back there for a trailer but if not just cut and splice.

Dont touch the wire on the trans just tap off the reverse lights all the way in the back of the truck.

 

[borahshadow]

Reverse is the thick green wire at the tail lights, there should be an extra one back there for a trailer but if not just cut and splice.

Dont touch the wire on the trans just tap off the reverse lights all the way in the back of the truck.

Yeah I figured that out last night just before you posted this. I tried the wire on the transmission and I couldn't figure out what it was for so I ended up just digging the green wire out of the bundle going to the back like you recommended.

Just out of curiosity what is that green wire on the transmission for? It only seemed to read like 2 volts... :S