For 1990-2009 cars

### System Description

The horn system consists of the following components:

• | HORN fuse

• | Horn relay

• | Horn switch

• | Horn assembly

• | Body control module (BCM)

### System Operation

• | The vehicle horns are 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 Content Theft Deterrent (CTD) Description and Operation.

- | 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.

### Circuit Operation

The BCM controls the horn operation, when the horn switch is pressed it closes to ground pulling the horn signal circuit low. When the BCM detects the drop in voltage in the horn switch signal circuit, it activates the low side drive horn relay output which supplies ground to the coil of the horn relay. This energizes the relay, which provide B+ voltage to 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.