What was found
3733, DURING CLIMB AT APPROXIMATELY 12,000 FEET RECEIVED AC ESS BUSS CAUTION & EMERGENCY LIGHT CAME ON. THE MESSAGE CLEARED & LIGHTS WENT OUT APPROXIMATELY 20 SECONDS LATER WITHOUT CREW ACTION. THE MESSAGE & EMERGENCY LIGHTS BEGAN TO CYCLE APPROXIMATELY EVERY 10 - 20 SECONDS, COMPLIED WITH QRH. R & R RELAY K1XD IAW AMM 24-51-27, OPERATIONS CHECKED GOOD IAW CR J AMM 24-51-27. OPERATION CHECK EMERGENCY LIGHTS IAW AMM 33-51-00, OPERATIONS CHECKED GOOD.