I have a2011 F250 CC 4x4 XLT . I have noticed lately that when I put the key in the ignition switch there is a buzzing sound coming from engine compartment that can be heard when you are outside of truck! This is with the key not moved to start the truck just in the ignition . Is this normal or should I be expecting something is wrong. The truck runs normal it just the sound with the hood up it is in the engine compartment just can't locate! You can start truck and it goes away. Stop engine then put key back in and it Will not do it again! Puzzling, has anyone an idea! Thanks!