What was found
DURING TEST OF EMER LIGHTS ON PRE FLIGHT WITH SELECTOR SELECTED ON DID NOT RECIEVE THE EMER LIGHTS ON CAS MESSAGE. UPON INSP, FOUND LIGHTS UNDER CREDENZA & DIVAN WERE NOT ILLUMINATED. TROUBLESHOT DOWN TO FAULTY ELPS NR 4, ELPS NR 3 & ELPS NR 2. ACCESSED TO ELPS NR 3 AND 2 IN LOWER E & E BAY. REMOVED FAULTY ELPS NR 4 & INSTALLED NEW ELPS. REMOVED BATTERY PACK & INSTALLED NEW BATTERY PACK. REMOVED BATTERY PACK & INSTALLED NEW BATTERY PACK. POWERED ON ACFT, PERFORMED OPS CHK OF EMERGENCY LIGHT SYS, OPS CHKD GOOD. CLOSED ALL ACCESS & RETURNED ACFT TO ORIGINAL CONFIGURATION. WORK DONE IAW AMM 33-53-13, 33-53-09 & 33-53-05. NO DEFECTS NOTED