What was found
DURING SERVICE CHECK FOUND FAULT EPSU(10WL) FWD L/ DEU B (300RH1), WHILE DOING EPSU SYSTEM TEST. DURING EPSU BATTERY TEST, EXTERIOR LIGHTS FAULT CAME ON TEST. -FOLLOWED TSM 33-51-00-810-830-A, REPLACED POWER- EMERGENCY SUPPLY, REPLACED EPSU BATT, CHECKED WIRING IAW STEP 4.B.(C). FAULT CONT'D. REPLACED DEU-B, FAULT STILL APPEARRED. CHECKED A/C WIRING IAW STEP 4.B.(E). WIRING GOOD. FAULT CONTINUED. ALL TROUBLESHOOTING WAS PERFORMED ON L1 DOOR. CON'T ON LP 3436188-2.