What was found
WHEN RELEASING PARKING BRAKE CYAN EICAS MESSAGE EMER BRAKE FAULT. BRAKES WERE STILL HOLDING ACFT. CYCLED THE LEVER, BRAKES RELEASED. CYAN MESSAGE DISAPPEARED. AFTER STARTING TAXI & SETTING PARKING BRAKE AGAIN, SAME ISSUE HAPPENED. HAD TO CYCLE LEVER MULTIPLE TIMES TO GET BRAKES TO RELEASE. RETURNED TO GATE. RFS. INTERROGATED CMC, FOUND FAULT CODES 32400015UT1 & 32400016UT1, NO FAULT CODES ON EICAS. PERFORMED FIM 32-41-00-810-863A UP TO STEP 7(P). CONTINUED WITH E175 FIM 32-41-00-810-866A FROM STEP 7(M) TO P(2) SUBTASK 32-41-00-813-761A & FOUND TO BE TRANSITORY. R & R EMERGENCY/PARK BRAKE VALVE IAW AMM 32-44-01-000/400-801A. CHKED GOOD & TAXI CHK GOOD. NO FURTHER DEFECTS. RTS.