Circuit/System Description
The Body Control Module provides a ground for the Horn printed circuit board relay within the underhood fuse block. The underhood fuse block will then provide B+ voltage to the horn control circuit, sounding the horn.
The body control module monitors the horn switch signal circuit, when the horn pad is pressed, the BCM detects the drop in the horn switch signal circuit and provides a ground for the horn PCB relay within the underhood fuse block. The underhood fuse block will then provide B+ voltage to the horn control circuit, sounding the horns
System Description
The horn system consists of the following components
- 15A circuit fuse
- Underhood fuse block (contains a non-serviceable PCB Horn relay)
- Horn switch
- Horn
- Body control module (BCM)
System Operation
- The vehicle horn is activated whenever the horn switch is depressed.
- The BCM commands the horns ON under any of the following conditions: When the content theft deterrent system detects a vehicle intrusion-For further information refer to «Theft Systems Description and Operation»(ref-544490-S38612816782013042400000) . When the keyless entry system is used to lock the vehicle, a horn chirp may sound to notify the driver that the vehicle has been locked. The notification feature may be enabled or disabled through personalization. For further information refer to «Keyless Entry System Description and Operation»(ref-544473-S09687507942013042400000) .
Circuit Operation
The BCM controls the horn operation, when the horn switch is pressed, it closes a switch pulling the horn signal circuit low. When the BCM detects the drop in voltage in the horn switch signal circuit, it energizes the PCB Horn relay which provides B+ voltage to the horn control circuit, sounding the horn.
When the vehicle is in the Off Power Mode the BCM will attempt to detect a stuck or continuously activated horn switch. When enabled, activation of the horn will be limited to 10 seconds to protect the horn from excessive use.