SYSTEM / Electrical System SECURITY HORN CIRCUIT 1. When the external alarm signal or password in- put error signal from ICF is input to the monitor unit, terminal #A3 is connected to the ground in- side the monitor unit. 2. Therefore, the security horn relay is excited. 3. When the security horn relay is excited, electrical current from fuse #9 operates the security horn. From Battery Fuse #9 Signal from ICF A3 Monitor Unit Security Horn Security Horn Relay T1V1-02-05-006 T2-5-21