What was found
#1 VHF RADIO STOPPED TRANSMITTING. SHORTLY AFTER, DURING LEVEL FLIGHT, IFR, 6000MSL, 120KN, ON ATC VECTOR IN HEADING MODE AND THE NAV SOURCE IN ILS2, THE AUTOPILOT MADE AN UNCOMMANDED, ABRUPT LEFT TURN AND PITCH UP. THE MASTER CAUTION ILLUMINATED ALONG WITH AN AUTOPILOT WARNING LIGHT AND THE AUTOPILOT TURNED OFF. CONTINUED THE ILS APPROACH WITH THE AUTOPILOT IN OFF MODE AND BY USING #2 VHF RADIO TO COMMUNICATE WITH CENTER. 07/25 RML NOTE: COULD NOT DUPLICATE AUTO PILOT FAULT ON GROUND AND NO DISCREPANCIES NOTED DURING T/S. COULD NOT MOC FLIGHT DUE TO WEATHER. WILL PERFORM FUNCTIONAL CHECKS THIS MORNING. PERFORMED MULTIPLE FUNCTION CHECKS. THIS AIRCRAFT HAS BEEN RETURNED TO REVENUE SERVICE, REF # MEC-012816.