i own a 2001 ford ranger xlt with a 3.0 engine. i noticed a wire harness with a red and green wire inside with an electrical connector on each wire hanging down underneath the truck by the drivers side back bumper(under the truck ) it seems to run along the frame rail towards the engine compartment. the truck starts, and all the lights work, does anyone have any idea were the connectors plug onto ? im stumped! looked underneath, but couldnt find any bare terminals. they have to plug onto something!!

 

That sounds like the connector for a trailer hookup

 

If you are not the first owner then they could be for Trailer brakes or canopy lighting