rear defrost buzzes until I push it
 

1987 rx7 na. When I start the car there is a buzzing noise. The first time I started the car it took about an hour of pushing buttons and I hit the rear defrost the buzzing stopped. This happens every time I turn the key on. Does anybody know the cause. My dash lights don't illuminate either. My turn signals in the dash illuminate and the brake light on the center display illuminate. Those are the only lights that work. Any ideas here. Thanks in advance for any help.

I should state my headlights, brake lights, turn signals every light on the exterior works

By buzzer noise you mean the shift sound/low coolant/low oil buzzer right?

It actually sounds different. Not as loud and a different tone