tail lights

I have a 93 silverado and have had some light problems in the past. It has one of those panic buttons on the dash and a black box stuffed up under the dash,When I bought the truck a year ago none of my lights worked in the back,Afriend of mine came by and in ten minutes had them all working,never did tell me what he did and is now unavailableto me . My question is this can I unhook the box under the dashand if so how do I wire the lights door locks horn and etc.? thanksfor any help PRATTFAM