Principles of Operation

Horn

Principles of Operation

NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

The SJB supplies the switched and control voltage to the horn relay (part of the SJB). When the horn switch (part of the steering wheel) is pressed, ground is supplied to the horn relay coil through the clockspring. The horn relay then energizes, sending voltage to the horn, enabling the horn to sound.

The horn switch is part of the steering wheel and sits behind the air bag. There are 2 sets of contacts on the horn switch that are separated by springs. One set of contacts is connected to ground and the other set is connected to the horn signal circuit. When the driver air bag module is pressed, it pushes on the top set of contacts and collapses the springs. When the springs collapse, it allows the contacts to touch and complete the circuit.

The SJB can also provide ground to the horn relay coil to sound the horn when the anti-theft system is armed, when the panic button is pressed on the remote keyless entry (RKE) transmitter, or to indicate a programming feature sequence.