What was found
RECIEVED A STEERING INOPERATIVE CAUTION MESSAGE AFTER RETRACTING GEAR, COMPLIED WITH QRH, MESSAGE REMAINED, RETURNED TO DEPARTURE, LANDED NORMAL USING DIFFERENTIAL BREAKING. NO HYD SYST 3 MESSAGE, NO OTHER EICAS MESSAGES, NO STEERING ON TAXI AFTER LANDING. AIRCRAFT REMOVED FROM SERVICE, TROUBLESHOT AND FOUND THE LT RVDT HARD FAILURE. R & R THE LT STEERING RVDT IAW AMM 32-51. OPS CHECKED GOOD.