As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI OUT WHILE IN "ARM" THE EMERGENCY LIGHTING SYSTEM STARTED TO FLASH. VERIFIED FAULT. WHEN SELECTED TO ARM LIGHTS CAME ON & STAYED ON. DISCHARGED UNTIL LIGHTS BEGAN TO FLASH. CHARGED BATTERIES FOR 90 MINS & THE FAULT PERSISTED. MORE TROUBLESHOOTING NECESSARY, 2 EMERGENCY LIGHT POWER SUPPLIES ON ORDER. REMOVED FAULTY AFT EMERGENCY LIGHT BATTERY, INSTALLED A NEW BATTERY. REMOVED FWD BATTERY & INSTALLED TESTED BATTERY. WORK PERFORMED IAW AMM 33-52-01.