Horn: Description and Operation

HORN

There are three separate conditions that can cause the horn to sound. The horn will sound if the driver presses the horn switch(es), when the vehicle security module is armed, or when the tire pressure module (TPM) is in the calibration mode. The horn system uses a horn relay to provide voltage to the horns, while the horn switches, vehicle security module and TPM provide the grounds to engage the horn relay. The horn switch is integrated into the air bag. For the removal and installation of the air bag, refer to Air Bag Systems.

The vehicle security module is located behind the right quarter trim panel. For the removal and installation of the vehicle security module, refer to Information Bus (Module Communications Network).

PRINCIPLES OF OPERATION

The horn relay is powered on both the control and controlled sides by circuit 1680 (OG/RD). When the horn switch is, the horn relay control circuit 460 (YE/LB) is grounded on one side of the switch, through the speed control ground circuit 848 (DG/OG) and by the powertrain control module (PCM) on the other side of the switch. The horn relay is then energized, allowing battery voltage to flow through the horn relay to each horn through circuit 1 (DB), enabling the horns to sound. When the vehicle security system is armed, the vehicle security module provides: a momentary ground to the horn relay control circuit 460 (YE/LB) to indicate the system is armed, and a continuous ground when an intrusion is detected. When the tire pressure system is placed in the calibration mode, the tire pressure module will provide an intermittent ground through circuit 460 (YE/LB) to alert the technician when each wheel is calibrated.