Horn: Description and Operation
INTRODUCTIONAn electric horn system is standard factory-installed equipment on this model.
Horn System
Two horn systems are offered on this model. The standard equipment horn system features a single low-note electromagnetic horn unit, while the optional dual horn system features one low-note unit and one high-note unit.
Each horn system is activated by a switch concealed beneath the driver side airbag module trim cover in the center of the steering wheel. The horn system is connected to a non-switched battery feed so that the system remains functional, regardless of the ignition switch position.
Following are general descriptions of the major components in the horn system. Refer to the owner's manual in the vehicle glove box for more information on the features, use and operation of the horn system.
SYSTEM OPERATION
Horn Switch
A center-blow, resistive membrane-type horn switch is installed on the back side of the driver side airbag module trim cover in the center of the steering wheel. When the center area of the airbag trim cover is depressed, the horn switch completes a circuit to ground for the coil side of the horn relay. The steering wheel and steering column must be properly grounded for the horn switch to function.
The horn switch is only serviced as a part of the airbag module trim cover. If the horn switch should fail, or if the airbag is deployed, the airbag module trim cover and horn switch must be replaced as a unit.
Horn Tower
Horn Tower:
The horn tower is integral to the turn signal cancel cam, which is installed in the steering column below the shaft lock shield and the clockspring. This unit provides turn signal cancellation as well as a constant electrical contact between the horn switch on the steering wheel and the horn feed wiring in the multi-function switch.
The horn tower protrudes from the upper surface of the turn signal cancel cam. The horn tower passes through holes in the steering column shaft lock shield and the hub of the clockspring, which causes the entire turn signal cancel cam to rotate with the steering wheel.
An electrically conductive disc, which is coated with a special synthetic grease, is integral to the lower surface of the turn signal cancel cam. An electrical contact on one end of the horn switch feed wire is inserted into the horn tower from the top of the turn signal cancel cam, and is held against the steering wheel side of the conductive disc by a spring and locking retainer. A spring-loaded horn contact that protrudes from the upper surface of the multi-function switch housing on the left side of the steering column rides against and remains in constant contact with the lower surface of the conductive disc.
The horn tower and turn signal cancel cam unit cannot be repaired and, if faulty or damaged it must be replaced. Refer to Turn Signal Cancel Cam in the Removal and Installation section of Lighting and Horns/Turn Signal and Hazard Warning Systems for the service procedures.
Horn Contact
Multi-Function Switch:
A spring-loaded horn contact is integral to the multi-function switch assembly, which is secured to the left side of the steering column. The horn contact receives the feed from the horn switch through the horn tower and turn signal cancel cam unit. A wiring circuit from the horn contact runs through the multi-function switch and its wire harness connector to the control coil of the horn relay in the junction block.
The multi-function switch also contains circuitry for the following functions:
- Turn signals
- Hazard warning
- Headlamp beam selection
- Headlamp optical horn
- Windshield wipers
- Windshield washers.
The information contained addresses only the multi-function switch horn contact. For information relative to the other circuits and switches that are integral to the multi-function switch. However, the horn contact cannot be repaired. If the horn contact or any other circuit of the multi-function switch is faulty or damaged, the entire multi-function switch assembly must be replaced. Refer to Lighting and Horns/Turn Signal Switch and Hazard Warning Switch Replacement.
Horn Relay
The horn relay is a International Standards Organization (ISO) micro-relay. The terminal designations and functions are the same as a conventional ISO relay. However, the micro-relay terminal orientation (or footprint) is different, current capacity is lower, and the relay case dimensions are smaller than those of the conventional ISO relay.
The horn relay is a electromechanical device that switches battery current to the horn when the horn switch grounds the relay coil. See Horn Relay in the Diagnosis and Testing for more information.
The horn relay is located in the junction block, which is located on the driver side end of the instrument panel in the passenger compartment.
If a problem is encountered with a continuously sounding horn, it can usually be quickly resolved by removing the horn relay from the junction block until further diagnosis is completed.
The horn relay cannot be repaired and, if faulty or damaged, it must be replaced.
Horn
The standard single, low-note, electromagnetic diaphragm-type horn is secured with a bracket to the Anti-Lock Brake System (ABS) access plate located behind the outer fender extension panel under the left headlamp. The high-note horn for the optional dual-note horn system is connected in parallel with and secured with a bracket just inboard of the low-note horn. Each horn is grounded through its wire harness connector and circuit to an eyelet on the left side of the dash panel, 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.
Central Timer Module
A Central Timer Module (CTM) is used on this vehicle when it is equipped with the optional Vehicle Theft Security System (VTSS). In addition to serving as the security system module, the CTM combines the functions of a chime/buzzer module, an intermittent wipe module, an illuminated entry module, and a Remote Keyless Entry (RKE) module in a single unit.
The CTM is also able to control and integrate many of the additional electronic functions and features included on models with this option. The CTM contains a central processing unit and interfaces with other modules in the vehicle on the Chrysler Collision Detection (CCD) data bus network.
The CCD data bus network allows the sharing of sensor information. This helps to reduce wire harness complexity, reduce internal controller hardware, and reduce component sensor current loads. At the same time, this system provides increased reliability, enhanced diagnostics, and allows the addition of many new feature capabilities.
The horn relay is one of the outputs that the CTM can control. The CTM is programmed to energize or de-energize the horn relay in response to certain inputs from the Vehicle Theft Security System (VTSS) and the Remote Keyless Entry (RKE) system. Refer to Body and Frame/Locks/Power Locks Systems for more information on the RKE system. Refer to Accessories and Optional Equipment/Antitheft and Alarm Systems/Vehicle Theft/Security Systems for more information on the VTSS.
The CTM is mounted under the instrument panel, to the inboard side of the left center instrument panel support. Refer to Instrument Panel, Gauges and Warning Indicators/Instrument Panel/Central Timer Module Replacement
For diagnosis of the CTM or the CCD data bus, a DRB scan tool and the proper Diagnostic Procedures are recommended. The CTM cannot be repaired and, if faulty or damaged, it must be replaced.