[factory2wdblazer's]

i recently did a power door conversion also. i used the complete door's off a 90 blazer and cut the top's off so the would my 73 blazer. i only have the harrness from the door jam's back...........from what i under stand i need a relay or some thing???? i did not remove the door's off the 90 blazer so i don't know how they where hooked up.....any body know