What was found
AIR TURN BACK - FLT 0332 - AFTER T/O ENROUTE FROM OMA TO PHX, NR 2 ENGINE EGT FLUXUATED FULL SCALE FROM 0 TO 1250, RED LIGHT CAME ON AND DIGITS DISAPPEARED, FLUXUATED BACK TO 0 AND DIGITS DISAPPEARED AGAIN. IN LIGHT CHOP TO SMOOTH CONDITIONS EGT GAUGE FAILED INTERMITTENTLY THROUGH OUT RETURN TO OMA, EGT DID NOT RESPOND TO THROTTLE MOVEMENT, NR 1 ENGINE OPERATED NORMALLY. NOTE: AIRCRAFT EXPERIENCED NR 2 ENGINE EGT OVERTEMP IN LIGHT TO MODERATE TURBULANCE (5 SECONDS) ON PREVIOUS FLT INTO OMA (FLT 0512), MAINTENANCE REMOVED AND REPLACED 2 EACH WIRING HARNESSES IAW BMM 77-21-01-4 FOR THIS EVENT. (FLT 0332) MAINTENANCE PERFORMED 70 PERCENT POWER RUN, NR 2 EGT WENT FROM NORMAL TO 1250 DEGREES C TO 0 DEGREES C A