Horn Removal/Installation

Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .)
Remove the set plate. (See SET PLATE REMOVAL/INSTALLATION .)
Remove the front bumper. (See FRONT BUMPER REMOVAL/INSTALLATION .)
Disconnect the connector.

Fig 1: Horn (LH And RH) Connector And Bolt
Courtesy of MAZDA MOTORS CORP.
Remove the bolt.
Remove the horn.
Install in the reverse order of removal.