What was found
UPON REACHING CRUISE @FL250 ENG #2 OIL PSI INDICATION OBSERVED AS WHITE DASHES. SECONDS LATER INDICATION RETURNED BUT SHOWED @ RED 0. IT FLICKERS BETWEEN WHITE DASHES AND ZERO. EVENTUALLY IT STAYED INDICATION W / FLUCTUATING VALUES. NO CAUTIONS/WARNINGS OR ANNUNCIATOR PANEL. RAN EMERGENCY AND ABNORMAL CHECKLIST 7.8 "LOW OIL PRESSURE" CHECKLIST, WHICH DROVE US TO COMMAND A SHUTDOWN DUE TO 0 PRESSURE CONSISTENTLY LESS THAN 44 PSI. OIL TEMPERATURE WAS NORMAL AT ALL PHASES OF FLIGHT. #2 ENGINE SHUTDOWN AND RETURNED TO THE FIELD. LANDING UNEVENTFUL. REMOVED FROM SERVICE. REPLACED THE THE #2 ENGINE INSTRUMENT WIRING HARNESS AND THE #2 MAIN OIL PRESSURE TRANSDUCER. OPS CHECK GOOD. LEAK CHECK GOOD. RETURNED TO SERVICE.