Chevy Wiring confusion...

[1offroadin4x4xj]

Working on the parking/turn/brake lights on my 91 S-10...kept the orginal front corner markers, ditched the front facing turn signal and the rear tailight housings. Researched this and didn't come up with much, but I want to wire the reverse connection into some brighter, small fog lights for night-time wheeling. On my XJ it was just cut, splice, and done...worked fine. I can't get any power to my lights when the truck is in reverse with the lights hooked up to the light green (reverse) wire w/ the light grounded. The only diagram I found for the wiring shows just a simple ground and reverse wire going to the reverse lights (but that same ground runs to every connection on the factory housings, it's split like 6 times). Do all four wires...yellow, brown, dark and light green need to be connected and all grounded at the same time for everything to work properly? I noticed on the front I had to splice the blue and black wire for the front turn signals together to get the corner lamps to come on in the absence of the other lights. The running light power is already grounded because my rock lights wire right into that connection and come on without the ground lead being connected to the frame. Confusing to say the least.