What was found
IN CRUISE FLT "FMC P/RST" ILLUMINATED, NO FMC DATA ON CAPTAIN'S NAV DISPLAY MAP MODE AND NO FMC DATA ON BOTH FMC CDU'S. DISPLAY OF VTK FOLLOWED BY MAP FAIL FLAGS ON CAPTAIN'S NAV DISPLAY. LNAV/VNAV DID NOT DISENGAGE. FMC, LT, RESTORED TO NORMAL OPS BEFORE FMC SOURCE SELECT SWITCH WAS MOVED OUT OF NORMAL POSITION. ACFT GROUNDED. PERFORMED BITE ON LT & RT FMC'S IAW AMM 34-61-801. BOTH FMC'S HAD SAME FAULT-PRESSURE POSITION LAT - RATE. PERFORMED FIM 34-61-824 ADIRS SHOWED NO FAULTS DETECTED AND OPS CK NORMAL. FMC LT & RT BITE CK NORMAL IAW FIM 34-61-801.