Horn: Description and Operation

INTRODUCTION
Following are general descriptions of the major components in the factory-installed horn systems.

SYSTEM OPERATION
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 on the conventional ISO relay

The horn relay is a electromechanical device that switches current to the horn when the horn switch on the steering wheel is depressed. See the Testing for more information on the operation of the horn relay.

The horn relay is located in the Power Distribution Center (PDC), in the engine compartment. Refer to the PDC label for horn relay identification and location.

If a problem is encountered with a continuously sounding horn, it can usually be quickly resolved by removing the horn relay from the PDC until further diagnosis is completed. The horn relay cannot be repaired and, if faulty, it must be replaced.

Horn Switch
Two horn switches are installed in the steering wheel, one on each side of the center-mounted driver airbag module. When either switch is depressed, the switch completes a circuit to ground for the coil side of the horn relay The steering wheel and steering column must he properly grounded for the horn switches to function.

The horn switches are serviced only as a set with their wiring. If either switch should fail, both switches must be replaced.

Horn
The standard single, low-note, electromagnetic diaphragm-type horn is secured to a bracket behind the left end of the front bumper. The horn is grounded through its wire harness connector and circuit to an eyelet near the Power Distribution Center (PDC), and receives battery feed through the closed contacts of the horn relay

If the vehicle is equipped with a dual horn option, a high-note electromagnetic diaphragm-type horn is connected in parallel with, and mounted next to, the standard low-note horn behind the front bumper.

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

CIRCUIT OPERATION
The horn system is powered by a 50 amp fuse located in the Power Distribution Center (PDC), cavity 1, which is HOT at all times on circuit F31. This circuit supplies voltage to the coil and contact side of the horn relay

When the operator presses the horn switch, a ground path is completed on the coil side of the horn relay through the switch. The horn relay, located in the PDC, then CLOSES the relay contacts. Voltage is passed through the CLOSED relay contacts on circuit X2 to the horns.

Flash-To-Pass (Optical Horn)
Circuit A3 from fuse 6, a 40 amp, in the Power Distribution Center (PDC) supplies battery voltage to the headlamp switch. The headlamp switch has an internal circuit breaker that connects circuit A3 to circuit L20.

In the OFF or PARK position, the headlamp switch feeds circuit L20 which connects to the multi-function switch. Circuit L20 powers the high-beam on circuit L3 when the operator flashes the headlamps with the turn signal stalk of the multi-function switch.