1976 Mercury Monarch buzzing in dash
 

I'm a new Mercury owner (1976 Monarch) and recently started cleaning the engine compartment. There is a new battery on the vehicle, but there was corrosion on the terminals. After I cleaned the corrosion off the terminals and some other areas under the hood a buzzing sound started when I put the key in the ignition. It wasn't doing this yesterday. The buzzing is loud, cominh from somewhere behind the steering wheel, starts when the key is put all the way in, and persists when the key is turned and the motor started. The car still runs fine, just has this buzzing sound now. Could this have something to do with the relays? Any help is much appreciated.

Thanks