What was found
WITH EMER LIGHTS ARMED AND A/C PWR TURNED OFF, ONLY CENTER CABIN EMER LIGHTS TURN ON. EMER LIGHTS TEST FROM PTP TESTED OK. REPLACED POWER SUPPLY UNIT AT AFT POSITION DUE UNIT FAILED INDICATION, REF AMM 33-51-38-400-001-A. REPLACED BATTERIES AT AFT, MID RIGHT AND FWD POSITIONS, REF AMM 33-51-38-000-002-A. AIRCRAFT NOW PASSES SIMULATED ELEC POWER LOSS TEST.