What was found
EMER DECLARED, LANDING UNEVENTFUL & ACFT NOT OVERWEIGHT. DURING CRUISE WHILE APPROACHING TOP OF DESCENT, SELECTION OF DIRECTOR TO WAY POINT FAILED TO ACCEPT WITH, UNABLE RTE MOD, MSG DISPLAYED. ACCOMPLISHED FMC INFLIGHT FAULTS BITE ON LT FMC RECEIVING A PGM FAULT. NO OTHER MSGS IAW FIM 34-61-00. RESET LT FMC CB IAW AMM 34-61-02. SYSTEM CHECKED NORMAL.