What are the two wires on a car horn connected to?
2 Answers
One end of the car horn is connected to the positive terminal of the power source, while the other end is connected to the negative terminal through a relay. The horn button controls the relay, thereby indirectly controlling the connection and disconnection between the horn and the battery's negative terminal. Horn wire connection method: The horn has only two wires. When connecting, the red wire should correspond to the red port, and the black wire should correspond to the black port. Separate the two wires of the horn and strip about 2 cm of insulation. Use scissors to trim the wire ends neatly, fold them in half, then insert the red wire into the red socket and the black wire into the black socket using the same method. For nut-direct compression type connections, form the wire ends into a circular shape and wrap them around the screw between the bolt and nut, then tighten the nut to secure. Always ensure the red wire connects to the red port and the black wire to the black port during connection.
When helping a friend fix their car, I noticed that car horns typically have two wires: one is the power wire, usually connected to the relay output or directly from the battery positive terminal, responsible for providing current; the other is the ground wire, directly connected to the metal part of the car body or the battery negative terminal, used to complete the circuit loop. Once the power wire is connected, the current flows through the horn unit and back to the ground wire, producing sound. If accidentally reversed or not securely connected, the horn may not work or produce strange noises. I’ve also encountered cases where an aged or damaged power wire caused a short circuit, blowing a fuse—reminding everyone to disconnect the battery before replacing the horn to prevent accidents. If the ground wire is rusty, it should be sanded to ensure low resistance. In fact, most cars have a horn relay, where the power wire connects to it first and is then activated by pressing the button. A simple check with a multimeter to measure voltage can help locate the issue.
