GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 Rendezvous - FWD 🢒 Body 🢒 Horns 🢒 Horns System Description and Operation

System Description

The horn system consists of the following components:

    • The horn fuse
    • The horn relay
    • The horn switch, the horn switch is part of the inflatable restraint steering wheel module
    • The horn, vehicle may be equipped with a one or two horn system
    • The body control module (BCM)

System Operation

The vehicle horn system is activated under the following conditions:

    • The horn switch is depressed.
    • The body control module (BCM) commands the horn on. The BCM commands the horn on under any of the following conditions:
      • When the content theft deterrent system detects a vehicle intrusion. For further information refer to Content Theft Deterrent (CTD) Description and Operation in Theft Deterrent.
      • When the panic button is depressed on the remote control door lock transmitter. For further information refer to Content Theft Deterrent (CTD) Description and Operation in Theft Deterrent.
      • 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 in Keyless Entry.
      • When the OnStar® system is used to sound the horn. For further information refer to OnStar Description and Operation in Cellular Communication.

Circuit Operation

Battery positive voltage is applied at all times to the horn relay coil and the horn relay switch. Pressing the horn switch applies ground to the horn relay control circuit. The BCM may also apply ground to the horn relay control circuit as described above. When the horn relay control circuit is grounded, the horn relay is energized and battery positive voltage is applied to the horn through the horn control circuit. The horn sounds as long as ground is applied to the horn relay control circuit.