What was found
DURING TAXI IN THE LEFT FMC BEGAN CYCLING ON AND OFF, REPEATED VTK FLAGS ON LEFT NAV DISPLAY ALONG WITH REPEATED LOSS OF THE FMC ON THE MENU PAGE OF BOTH CDUS NO FMC ISSUES DURING FLIGHT. GROUNDED - YES. PERFORMED ACARS CMU RESET, OPS CHECK SUCCESSFUL, FMC STEADY ON VTK GOES OFF, NO FURTHER DEFECTS NOTED, REF FIM 34-61 TASK 838, A/C OK FOR SERVICE.