What was found
AIRCRAFT WAS GROUNDED: WITH FLAPS 5 SELECTED LE FLAPS TRANSIT LIGHT ILLUMINATED. RAN CHECKLIST NO.4 PANEL LEADNG EDGE PANEL SHOWED IN TRANSIT. AFTER SLOWING FOR APPROACH LE FLAPS EXT LIGHT ILLUMINATED AND STAYED ON FOR THE REST OF APPROACH. NO.4 PANEL SHOWED NORMAL EXTENSION. EMERGENCY DECLARED. ACCOMPLISHED BITE FSCU FOUND FAULT MS-27-81223 F4 PROX EXTEND SENSOR FAULT. INSPECTED SENSOR FOUND WIRE MISSING INSULATION AND SHORTING OUT. ACCOMPLISHED SPLICING PROCEDURE 24-40-00-2 AND OPS CHECK SYSTEM. OK FOR SERVICE ALL INDICATIONS NORMAL, (WIRE #2001B-20).