What was found
(CAN) AS THE ACFT WAS ABOUT TO LIFT FOR TRIP, THE NR 2 ENG FIRE WARNING LIGHTS ILLUMINATED ALONG WITH THE "FIRE ENGINE 2" AUDIO MESSAGE FOR 1 ITERATION. THE FIRE WARNING WENT OUT MOMENTARILY. CHANGED HEADING TO TROUBLESHOOT AND THE WARNING CAME ON AGAIN FOR 1 ITERATION, THEN CLEARED. NO SIGNS OF FIRE. NO FURTHER WARNINGS. THERE WAS A SUSPECTED INTERMITTENT WIRING FAULT CAUSING FLAME DETECTOR FALSE WARNING. FLAME DETECTOR AND HARNESS ASSY REPLACED.