Horn Relay: Description and Operation

The horn relay operates through a direct wire input to the FCM from the horn switch (FCM pin 17) , or a PCI Bus message from the BCM. The relay responds to the horn switch, remote door lock and VTA alarm functions. The horn relay is powered through low side control on pin 10 of the FCM. Under normal operating conditions, if the horn is pressed for longer than 30 seconds, the FCM will automatically deactivate the horn to prevent damage to it. The FCM will re-activate control of the relay after a 25 second cool-down period. This circuit is electronically controlled and continuously monitored for malfunctions.