As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STANDBY BUS OFF EICAS MESSAGE ON GROUND. (<P>ACCOMPLISHED FIM 24-33 FT 803 AND FOUND AC STBY BUS OFF RELAY K138 AT FAULT. SWAPPED WITH RELAY K835.- AFT LAV EXH FAN 1 AND PERFORMED STBY POWER OPS TEST PER AMM 24-33-00. OPS CHECK OK. ALSO PERFORMED AFT LAV EXH FAN 1 TEST PER AMM 21-26-01 AND OPS OK.</P>)