What was found
CREW REPORTED ON APPROACH 6 INTO KTEB, PRIOR TO FAF, AMBER BRAKE 50% DEGRADED CAS MESSAGE POSTED. EXECUTED GO-AROUND, WITH TOWER INSTRUCTIONS. VECTORED TO FIGURE OUT THE SITUATION. ASKED FOR DIVERSION INTO KEWR. WERE GIVEN DELAYED VECTORS DUE TO AN EMERGENCY AIRCRAFT THAT WAS DIVERTING INTO KEWR. THE TOWER NOTIFIED US THAT HE WAS DECLARING AN EMERGENCY ON OUR BEHALF. LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT BRAKE CONTROL SYSTEM WITH NO DEFECTS NOTED. MAINTENANCE RE-RACKED BRAKE CONTROL UNIT AND BLED BRAKE SYSTEM. OPERATIONAL AND LEAK CHECKS PERFORMED WITH NO DISCREPANCIES, AIRCRAFT RETURNED TO SERVICE.