Horn - Operation

OPERATION

Each horn has a path to ground at all times through its wire harness connection to an eyelet terminal secured to the body sheet metal. The horns are completely controlled by a fused B(+) output received through a relay soldered onto the Printed Circuit Board (PCB) within the Power Distribution Center (PDC) and controlled by the Body Control Module (BCM) (also known as the Common Body Controller/CBC).

Within the two halves of the horn housing are a flexible diaphragm, a plunger, an electromagnetic coil and a set of contact points. The diaphragm is secured in suspension around its perimeter by the mating surfaces of the horn housing. The plunger is secured to the center of the diaphragm and extends into the center of the electromagnet. The contact points control the current flow through the electromagnet.

When the horn is energized, electrical current flows through the closed contact points to the electromagnet. The resulting electromagnetic field draws the plunger and diaphragm toward it until that movement mechanically opens the contact points. When the contact points open, the electromagnetic field collapses allowing the plunger and diaphragm to return to their relaxed positions and closing the contact points again. This cycle continues repeating at a very rapid rate producing the vibration and movement of air that creates the sound that is directed through the horn trumpet outlet.

The horns as well as the hard wired input circuits for the horns may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information.