As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FIRST OFFICERS DISPLAY NOT INDICATING PROPERLY IN AUTO MODE. BOTH DISPLAYS IN AUTO MODE AND SUDDENLY FO'S DISPLAY INDICATED HEAVY RETURNS IN WX AND WX+T. CAPTAINS DISPLAY INDICATED NOTHING. CLEAR OF ANY WEATHER. ATTEMPTED TO DE-SELECT AND RE-SELECT WX ON FO'S DISPLAY. SAME CONDITION. APPEARS TO FUNCTION OK IN MANUAL MODE. GROUNDED - YES. REMOVED AND REPLACED WEATHER RADAR CONTROL PANEL REF B737-900 AMM 34-43-91 OP CK GOOD.