95 1500 4x4 problems

ok, so ive had this problem for a couple of years and never really got around to fixing the problem. my 4x4 wont engage because my diff locker wont engage. but ive put a new locker in so im not sure what the problem is. i was thinking of putting in a new transfer case switch, but i dont know for sure if that sends the signal for the locker or not, im assuming whatever sends the signal is bad and im sure that it could be more than just this problem, but im sure its electrical. if anyone could give me a good place to start it would be appreciated because i cannot find an electrical diagram anywhere for this system. thanks.