What was found
PWS FAIL DISPLAYED ON BOTH NAV DISPLAYS IN TERRAIN MODE ON APPCH BELOW 30'. GROUNDED - YES. PERFORMED WEATHER RADAR BITE PER B737-900 FIM 34-43 TASK 801. TEST FAILS AND PRODUCES "ANT" ANTENNA FAULT. ACCOMPLISHED WIRING CHECKS BETWEEN R/T CONNECTOR D189 AND DRIVE UNIT D119 REF B737-900 WDM 34-41-11, NO FAULTS NOTED. REPLACED ANTENNA DRIVE UNIT AGAIN, OPS TEST PASS PER B737-900 AMM 34-43-41. REFERENCE FIM 34-43-815 ROCKWELL/BOEING NOTE REGARDING KNOWN CONDITION OF DRIVE UNIT CIRCUITRY CAUSING OCCASIONAL PWS FAIL MESSAGES ON TAKEOFF OR APPROACH. OFF DRIVE UNIT PLACED ON ROH. REPAIR CONFIRMATION SUCCESSFUL, WXR BITE TEST PASS FIM 34-43 TASK 815.