Using Your Horn You can use your vehicle’s horn to let other drivers know you are there or to warn others of a hazard. It is important to know when to use your horn, and when not to. It is safer to slow down or stop instead of honking your horn. Use your horn to: ? Avoid collisions (when necessary). ? Alert another driver of a hazard. ? Alert oncoming traffic on narrow mountain roads where you cannot see at least 200 feet ahead of your vehicle.