Ford Escort Buzz

My 96 Escort has developed a buzzing sound that is definitely electrical. It used to be intermitent but now occurs at all times when the engine is on. It seems to be coming from the passenger side air bag. The strange thing is my high beams have stopped working (turn on high beams and the lights die) but my low beams are ok. Noise stops when I turn on lights, or engage parking brake. It also changes pitch when any of the other dashboard lights are light (i.E. Turn signal or hazards or rear defrost). Any ideas