Horn System (Service Information): Operation

The horn system components operate on battery current received through non-switched fused B(+) circuits so that the system will remain operational, regardless of the status of the ignition switch (Keyless Ignition Node/KIN). The Body Control Module (BCM) controls the output of battery current to the horns through a horn relay located within the front Power Distribution Center (PDC). The BCM controls the relay based upon internal programming as well as electronic message inputs received from the Steering Column Control Module (SCCM) or the Radio Frequency Hub Module (RFHM) over the Controller Area Network (CAN) data bus.

The vehicle operator can control typical horn system signaling through the horn switch contacts within the hub cavity of the steering wheel. When the Driver Airbag (DAB) trim cover in the center of the steering wheel is depressed, it provides a hard wired analog input to the SCCM. The SCCM then sends an electronic horn switch status  message to the BCM over the CAN data bus.

In addition, the RFHM sends electronic horn request  messages to the BCM over the CAN data bus in response to inputs received from the FOB with Integrated Key (FOBIK) Remote Keyless Entry (RKE) transmitter in vehicles with the PEKG system. Lastly, as the Vehicle Theft Security System (VTSS) controller, the BCM can activate the horn system based upon programming and both hard wired and electronic message inputs from the various VTSS components.

The horns can be activated by the BCM to support each of the following features:

• Remote Keyless Entry System  - Remote Keyless Entry (RKE) system Lock  request audible verification.
• Remote Keyless Entry System  - Remote Keyless Entry (RKE) system Panic  mode audible alert.
• Remote Start System  - Remote Start System Start  request audible verification.
• Vehicle Theft Alarm  - Vehicle Theft Alarm (VTA) audible alarm.

The RKE system Lock  request audible verification is a customer programmable feature, which allows the feature to be enabled or disabled to suit individual preferences. Refer to CENTER, ELECTRONIC VEHICLE INFORMATION, OPERATION .

The hard wired circuits between components related to the horn system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the horn system or the electronic controls and communication between modules and other devices that provide some features of the horn system. The most reliable, efficient and accurate means to diagnose the horn system or the electronic controls and communication related to horn system operation requires the use of a diagnostic scan tool.