A: These models are equipped with a Body Control Module (BCM). Several systems are linked to a centralized control module that allows simple and accurate troubleshooting, but only with a professional-grade scan tool. The Body Control Module governs the Door Locks, the power windows, the ignition lock and security system, the interior lights, the Daytime Running Lights system, the horn, the windshield wipers, the heating/air conditioning system and the power mirrors. In the event of a malfunction with this system, have the vehicle diagnosed by a dealership service department or other qualified automotive repair facility. On 2009 and earlier models, remove the left (driver's side) Headlight housing. On 2010 through 2012 models, remove the left (driver's side) inner fender splash shield. On 2013 and later models, remove the left or right inner fender splash shield to replace the appropriate horn. On 2012 and earlier models, the horns are mounted on one side and on 2013 and later models, one horn is mounted on each side of the vehicle. Remove the mounting nut (The horn mounting nut can be accessed after the left headlight is removed), then detach the horn and disconnect the electrical connector. Installation is the reverse of removal.