What was found
RADAR WHILE IN AUTO MODE SWITCHES ITSELF TO MANUAL MODE. MANUAL MODE SEEMS TO WORK NORMAL. GROUNDED - YES. SEMI DUPLICATED DISCREPANCY. WHEN IN AUTO AS THE SWITCH WAS PUSHED IN IT WOULD DISPLAY AUTO AND THEN MANUAL FOR ABOUT A SECOND, THEN SHOWED AUTO. LEFT RADAR RUNNING FOR A WHILE AND DID NOT CHANGE TO MANUAL. REMOVED AND INSTALLED NEW RADAR CONTROL PANEL, REF B737-900 AMM 34-43-91-000-801 WEATHER RADAR CONTROL PANEL REMOVAL, REF B737-900 AMM 34-43-91-400-801 WEATHER RADAR CONTROL PANEL INSTALLATION. PERFORMED INSTALL TEST, REF STEP E. INSTALLATION TEST B737-900 AMM 34-43-91. SYSTEM TEST NORMAL. DID NOT NOTICE THE ABOVE MALFUNCTION.