Q: When I unlock the door with key the horn sounds until I start the engine

Hello, thanks for writing in. The horn is being set off by the body control module. This module contains the anti-theft controls and if it does not get a remote signal to disarm the system then this will occur. There is no easy way to disable this if there is a problem with the body control module or if it is just because you do not have a remote. If that is the case the best fix is a new remote. In order to disable this system a bypass kit would need to be installed. If you need to have this anti-theft system problem fixed, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose and repair this honking issue.