What was found
NR 1 NAV INOP IN VOR DISPLAY ON PILOT'S HSI UNLESS DME WAS LOCKED ON. PROBLEM CAUSED BY REMOTE AREA/NAV SELECT LIGHT BEING IMPROPERLY WIRED TO A LAMP ASSEMBLY WITH NO ISOLATED GROUND. WITH A HARD GROUND ON PIN 16 OF THE KN74, IT WAS STUCK IN LOCALIZED MODE UNLESS A POSITIVE FLAG FROM THE DME LOCK ON 'FIXED' THE PROBLEM. INSTALLED AND WIRED PROPER LIGHT ASSEMBLY FOR NORMAL OPERATION. INSTALLATION NOTES SHOULD BE READ VERY CAREFULLY.