What was found
L ELEV PITOT LIGHT ON WHEN TAXING TO THE GATE. GROUNDED - YES. L ELEV PITOT LIGHT "OUT" AND OPERATING NORMAL. PULLED C/B FOR L ELEV PITOT HEATER AND LIGHT ILLUMINATED. RESET BREAKER. DUE TO HISTORY AND REPAIR INFORMATION ON WINDOW AND PITOT HEAT PANEL, REPLACED P5-9 PANEL PER B737-800 AMM 30-41-41. L ELEV PITOT LT ILLUMINATES ONLY IN "AUTO" POSITION. FOUND DAMAGED WIRE BEHIND P18-3 PANEL. REPAIRED WIRE W0018-0152-22 AND RESECURED BUNDLE TO PREVENT FURTHER CHAFFING PER B737 SWPM 20-10-13. CLOSED OUT PANEL P18-3 AND REMOVED ALL FOD. OP CHK OF PITOT HEAT SYSTEM IN AUTO MODE PER AMM 30-31-00 REQ. P5-9 INSTL TEST PASS AMM 30-41-41.