The Intermountain 2014 release of their F-Units require some special attention when installing a decoder. There are three locations which require attention to make sure the motor and headlight LED are completely isolated. If the motor is not insulated, you'll hear a buzzing sound when the locomotive is placed on your layout. I would suggest trying to program the locomotive on an isolated service mode programming track. If you're successful in programming, the motor is properly isolated.
1. The motor has to be removed from its mount and Kapton tape needs to be placed from the bottom of the motor around both sides to insulate the motor tabs. The tabs are soldered randomly to the motor so care must be taken to make sure the Kapton tape insulates the motor tabs.
2. The inside of the frames need Kapton tape placed where the motor sits in the chassis frames to further insulate the motor from the frame.
3. The A unit headlight uses some very thin heat shrink that sometimes doesn't insulate the LED properly or gets torn and causes a short. When necessary, Kapton tape should be added to the frame to insulate the LED.