I recently install a system in my Nissan car. One pioneerCd deck, I Power Accoustic Amplifier Demon Series, 1 five way 6x9 Amp and a power accoustic pre amp- PWM 19. Now anytime I sound my car horn I hear it on the ^x( speakers. I have changed each equipments and the same thing. I have ground the amp and the deck to the car chassis. Ground from Battery to the car body and engine to the body, but still happening. A friend told me it could be the Brand of RCA jacks I used ...... can any one help me please??