Why Does a Car Horn Sound by Itself?

[MacEva]

Car horns sounding by themselves are caused by faulty contacts in the horn, preventing the horn switch and relay from automatically disengaging. Below are the specific reasons why a horn may not sound: Poor Sealing Leading to Water Ingress: The horn is internally sealed, but if the sealing is poor, water vapor can enter during car washing, causing the contacts to become damp and malfunction. Poor Contact at the Electromagnetic Coil Terminal: The terminal connections of the electromagnetic coil inside the horn are made of aluminum. If the insulating varnish on the enameled wire ends is not properly removed or if the crimping of the terminals is loose, poor contact can occur, leading to the horn not sounding. Contact Erosion Due to Prolonged Use: Prolonged use of the horn can cause the contacts to erode, creating resistance. This reduces the current passing through the electromagnetic coil, preventing it from attracting the armature to vibrate the diaphragm properly, resulting in the horn not sounding. However, when the horn is pressed continuously, a momentary surge of strong current can still pass through the resistance, allowing the horn to work intermittently.