What was found
DURING CLIMB AURAL WARNING AND TAKE OFF CONFIGURATION WARNING LIGHTS CAME ON WHEN PASSING FL 310. CHECKLIST PERFORMED AND LIGHTS AND SOUND WENT OFF WHEN PASSING 10,000 FT DURING DESENT. REMOVED AND REPLACED FSEU IAW B737-800,OPS CHECK GOOD. CONFIDENT CHECK FLIGHT OK. P/N ON 285A1200-2, S/N ON 000785.