What was found
AHM DETECTED WELS MMSG (33-11621) CLASS 21. REMOTE WELS CONTROL UNIT LAMP DRIVER POWER CIRCUIT IS FAILED, REF CONFIGURATION DRAWING 787 WELS 2500DD15923 AND FIM DMC-B787-A-33-50-F1-C3A-421A-A TO CONFIRM/ISOLATE FAULT. M3351WG01_CLASS21 (ROW 1D). CARRIED BY ELB VERIFIED FAULT. REPLACED CLASS 21 WCU, BUT FAULT REMAINED ACTIVE. REPLACED PROX LED ASSY AT SEAT 3F. FAULT WENT INACTIVE. PERFORMED QUICK & FULL EMERGENCY LIGHTING SYSTEM TEST. NO FURTHER ADD FAULT: 33-11621 FAULTS. AMM REF DMC-B787-A-33-51-07-01A-720A-A. VERIFIED ALL SEAT EMERGENCY LIGHTING. OPS CHECKED GOOD. A/C OK FOR SERVICE.