Principles Of Operation
WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.
When the horn switch is pressed, circuit 1 (DB) grounds the SJB. The SJB then grounds the horn relay control circuit 1323 (OG/RD). This energizes the horn relay, allowing battery voltage to flow through the horn relay to the horn through circuit 6 (YE/LG), enabling the horn to sound. When the vehicle security system is armed, the SJB provides a momentary ground to the horn relay control circuit 1323 (OG/RD) to indicate the system is armed, and a continuous ground when an intrusion is detected or the panic alarm is activated.