What was found
ON TAXI OUT, POWER BRAKE CIRCUIT BREAKER TRIPPED ,ANTI-SKID CAUTION LIGHT ILLUMINATED FOLLOWED BY THE LOW BRAKE PRESSURE CAUTION LIGHT. AIRCRAFT WAS TOWED BACK TO RAMP. TROUBLESHOT SYS IAW THE WDM 32-40-01. FOUND NO DEFECTS, COULD NOT GET THE SYSTEM TO FAIL. MFG SUPPORT SUGGESTED REPLACING THE DIODE ON RELAY KX067 FROM X1 TO X2. REPLACED DIODE AND OPS CHECKED. SYS OPS NORMAL.