What was found
WITH LIGHTS TEST SWITCH IN DIM, EXEC, CALL AND MSG LIGHTS ON CA MCDU FLASHED DIM TO BRIGHT APPROXIMATELY 60 CPS. OK IN BRIGHT. ACFT GROUNDED. UNABLE TO DUP/VERIFY DISCREPANCY. UPON ACFT POWER UP, REF MM 34-61-00, TEST OF THE ANNUNCIATORS OPS NORMAL W/ DIM, BRIGHT SWITCH, DCU BRIGHTNESS AND FMC MCDU FACEPLATE BACK GROUND LIGHTING GOOD. NO HISTORY LAST 90 DAYS. GROUND VERIFICATION, OPS NORMAL.