As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT IN BASE MAINTENANCE: IWHILE PERFORMING A TEST OF THE EMERGENCY LIGHTING SYSTEM FAULT MESSAGE FOR INT LOAD FAULT AT EPSU AFT L (13WL) OCCURRED. REPLACED POWER SUPPLY 13WL AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK PER AMM 33-51-38-400-001-A.