As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU MASTER CAUTION LIGHT ILLUMINATED WHEN ELECT POWER TRS TO ENG DRIVEN GENERATORS REMAINS ILLUMINATED WHEN APU SHUTDOWN. INTERROGATED CDU PERFORMED BITE TEST ON APU NO RECENT FAULT OR ANY HISTORY FAULTS NOTED ON ANY LEGS, SHOT DOWD AC POWER CYCLE AC POWER APU MASTER CAUTION LIGHT IS OFF PERFORMED SECOND APU BITE TEST OK. (K)