interior lights crown victoria

 Have a 94 crown victoria that was a FBI unit with intercepter package the problem i have is the interior lights do not come on when the doors are opened . I do have power at the fuse, and when i turn the light switch control all the way to the left the lights do come on. I can not find any wiring diagrams that address this circuit. Everything else on this fuse works. Does this circuit have a relay ?. If so where whould it be located? A wiring diagram would be helpful but any infomation on which wire may be cut or removed to cause this problem would be much appreciated