As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU AIR SHUTOFF VALVE WILL NOT GO TO CLOSED POSITION. DEACTIVATED APU AIR BLEED SHUTOFF VALVE IN CLOSED POSITION. *S/D* REPLACED RELAYS K10280 AND K23 IN P37 PANEL WITH NO HELP. REPLACED APU BLEED VALVE, CLEARED ECU AND DUCT PRESSURE WAS NORMAL.