Horn: Description and Operation

HORN SYSTEM
DESCRIPTION
A dual-note electric horn system is standard factory-installed equipment on this model. The standard equipment horn system features one low-note horn unit and one high-note horn unit. The horn system uses a non-switched source of battery current so that the system will remain functional, regardless of the ignition switch position. The horn system includes the following components:
- Clockspring
- High-line Central Timer Module (CTM)
- Horns
- Horn relay
- Horn switch

Refer to Clockspring in the Description and Operation of Passive Restraint Systems for more information on this component. Refer to Central Timer Module in the Description and Operation Instrument Panel Systems for more information on this component.

OPERATION
The horn system is activated by a horn switch concealed beneath the driver side airbag module trim cover in the center of the steering wheel. Depressing the center of the driver side airbag module trim cover closes the horn switch. Closing the horn switch activates the horn relay The activated horn relay then switches the battery current needed to energize the horns.

Refer to the owner's manual in the vehicle glove box for more information on the features, use and operation of the horn system.

Central Timer Module
The high-line Central Timer Module (CTM) can also operate the horn system. A high-line CTM is used on high-line versions of this vehicle. The CTM combines the functions of a chime/buzzer module, an intermittent wipe module, an illuminated entry module, a remote keyless entry module, and a vehicle theft security system module in a single unit.

The high-line CTM also controls and integrates many of the additional electronic functions and features included on models with this option. The horn relay is one of the hard wired outputs of the CTM. The high-line CTM is programmed to energize or deenergize the horn relay in response to certain inputs from the Remote Keyless Entry (RKE) system and/or the Vehicle Theft Security System (VTSS).

Refer to Central Timer Module in the Description and Operation Instrument Panel Systems for more information on the high-line CTM. Refer to Remote Keyless Entry System in the Description and Operation of Power Lock Systems for more information on the RKE system. Refer to Vehicle Theft Security System in the Description and Operation of Vehicle Theft/Security Systems for more information on the VTSS.

HORN
DESCRIPTION
The dual electromagnetic diaphragm-type horns are standard equipment on this model. The low-note horn is secured with a bracket to the right front inner fender shield just ahead of the right front wheel house in the engine compartment. The high-note horn is connected in parallel with and secured with a bracket just forward of the low-note horn. Each horn is grounded through its wire harness connector and circuit to an eyelet on the right inner fender shield, and receives battery feed through the closed contacts of the horn relay.

The horns cannot be repaired or adjusted and, if faulty or damaged, they must be individually replaced.

OPERATION
Within the two halves of the molded plastic 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 outlet.