What was found
ETOPS SIGNIFICANT SYSTEM, APU INOP, OIL QT ZERO. RAN APU, THEN PHYSICALLY VERIFIED OIL QTY WITH SIGHT GAUGE, LEVEL IS FULL AND QTY INDICATION IN CKPT READS FULL ALSO. BIT CHECK ECU FOUND "A/C START CIRCUIT" MSG, TROUBLE SHOT PER FIM 49-11-00, NO DEFECTS NOTED. REMOVED AND REPLACED ECU PER MANAGEMENT AS PRECAUTIONARY PER AMM 49-61-05. OPS CHECK OK, SECURITY CHK OK.