GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 XLR 🢒 Body 🢒 Horns 🢒 Horns System Description and Operation

System Description

The horn system consists of the following components:

    • Horn relay
    • Inflatable restraint steering wheel module coil
    • Horn switch
    • Horn assembly
    • 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 horns on. 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 Content Theft Deterrent (CTD) Description and Operation .
       - When the panic button is depressed on the remote control door lock transmitter--For further information refer to Keyless Entry System Description and Operation .
       - When the keyless entry system is used, a horn chirp may sound to notify the driver that a keyless entry event has occurred. The notification feature may be enabled or disabled through personalization--For further information refer to Keyless Entry System Description and Operation .

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 body control module (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 horns through the horn control circuit. The horns sound as long as ground is applied to the horn relay control circuit.