As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE TAXING OUT THE PWR BRKS CB TRIPPED, STOPPED THE ACFT AND SET THE PARKING BRAKES BEFORE WE LOST ALL BRAKE PRESSURE. WE SHUT OFF THE ENGINES AND WERE TUGGED BACK TO AVFLIGHT. WE NEVER NEEDED OR USED THE EMER. BRAKES. REPLACED BRAKE PUMP PRESSURE SWITCH. IAW CESSNA 560XL MM 32-44-20. OPS CHECK GOOD.