What was found
DURING CRUISE AT FL410 A TCAS IN STBY DIDPLAYED ON THE MFD AND A WHITE XPDR IN STBY CAS MESSAGE DISPLAYED. TRANSPONDER WAS IN A/RA BUT TRANSPONDER CODE WAS YELLOW ALONG WITH FLIGHT ID. ATC NOT ABLE TO GET ANYTHING BUT A PRIMARY RETURN, REGARDLESS OF WHICH TRANSPONDER SELECTED. PERFORMED THE OPS CHECKS OF THE TRANSPONDER WITH SATISFACTORY RESULTS REF CL 350 AMM 34-54-01. PERFORMED THE FOLLOW ON CHECKS AFTER RERACKING THE JB4 WITH SATISFACTORY RESULTS UP TO THE RETRACTION FUNCTIONAL CHECKS IAW AMM 24-63-13. JACKED AIRCRAFT & PERFORMED MULTIPLE OPS MLG SWINGS, NO DEFECTS NOTED IAW AMM 32-30-00. RETURNED TO ITS ORIGINAL CONFIGURATION.