What was found
AHM DETECTED WELS MMSG {33-11726} *CLASS 26 - DOOR 3 LT FWD SEAT REMOTE WELS CONTROL UNIT LAMP DRIVER POWER CIRCUIT IS FAILED. REF FIM DMC-B787-A-33-50-F1-E7A-421A-A TO ISOLATE FAULT. REF CONFIG DWG 2500DD15835 TO LOCATE WCU CLASS 26 M3351WG04 UNDERNEATH SEAT 39D. WCU AT SEAT PAN 43D SWAPPED TO WCU AT SEAT PAN 39D, MAINT MSG:33-11726 ERASED. NEW WCU REPLACED ON SEAT PAN 39D . ORIGINAL WCU ON SEAT PAN 43D RESTORED BACK. MAINT MSG 33-13126 TRIGGERED AFTER WELS SYS STABILIZED. WCU SOFTWARE ON 33 ELS DB LOADING CARRIED OUT IAW AMM B787-A-33-51-07-04A-750A-A TO PRIMARY WCU AT DOORS 1L, 2R, 3L, 4R.SOFTWARE CONFIG CHKD & MM 33-13126. EMERGENCY LIGHTS OPS TESTED, ALL CABIN EXIT SIGNS & SEAT PROX LIGHTS SATIS.