The horn system is supplied via horn relay R3, located in engine bay junction unit B01, via a direct line from the battery protected by control unit fuse F10.The coil for relay R3 is energized with an earth signal when one of the switches on the steering wheel is closed; connected via the clock spring of stalk unit H05.This signal reaches pin 21 of connector B of engine bay junction unit B01.Relay R3 thus supplies horn P05 from pin 28 of connector B.Horn P05 and stalk unit H05 are connected to earth C10 at pins 2 and 16 respectively.