The horn system is supplied by the R3 horn relay in the luggage compartment junction unit B001, the line protected by fuse F10 in the same junction unit and directly by the battery.The relay coil is energized by an earth signal when the switch on the steering wheel closes and is connected via the clock spring coupling to the controls on the steering wheel D110 (inside the steering column switch unit H005). The relay supplies the high tone horn P010 and the low tone horn P011.