For each of the headlights, the supporter spring, which is to fix the bulb and is a part of the earth circuit, does not have sufficient strength to hold the bulb, and therefore, the pressure of the contact points in the earth circuit may become insufficient over the years depending on the installation of the connector. If this occurs and a spark is generated between the contact points, the heat from the contact points may cause the supporter spring to deform, and in the worst case, that headlight would stop working.