What was found
ACCOMP ASA T/C 78273000. RECORDED FAULT CODE 75-30452 THE VBV POSITION SIGNALS DISAGREE #2 ENG SHORT TIME FAULT. GROUNDED - YES. C/W B737-900 FIM 75-32 TASK 803, MEASURE THE RESISTANCE BETWEEN THE VBV ACTUATOR & EEC DP1010 AND DP0909 (VBV VERSION 2) ALL RESISTANCE VALUES WITHIN LIMITS AND NO SHORT TO GND. C/W WIRING CHECKS EEC TO HMU REF FIM 75-32 TASK 804 CH A & B = 18.5 OHMS NO SHORT TO GND. PERFORMED EEC ACTUATORS TEST, NO FAULTS FOUND. AFTER ACT TEST INTERROGATE EEC CONTROL LOOP INPUT MONITORING FOR VBV FOUND CH B BEGINS INCREASING VALUE TO OVER 4 DEG SPLIT BETWEEN CHA &B. #2 ENGINE EEC BITE SHOWS MSG 75-10452 AND 75-20452 SINGLE CHANNEL FAULTS ON ALMOST ALL FLIGHT LEGS RECORDED BUT NO LONGER SHOWS DUAL CHANNEL FAULT 75-30452. SUSPECT DEFFECTIVE EEC FROM INSTALL ON 8/8/2022 DEFECT 60421683. REMOVED AND REPLACED EEC REF B737-900 AMM 73-21-60. ALL TESTS PASS NO NEW MSG FROM EEC AFTER EEC BITE/ENGINE RUN. ALL SOFTWARE EFFECTIVE AND COMPATIBLE WITH OTHER ENGINE AND FMC MEDB. ETOPS SIGNIFICANT SYSTEM GROUND VERIFICATION SUCCESSFUL.