There is a crucial part in your car named headlamp dimmer switch. The location of the dimmer switch is in the turn signal switch assembly or it is mounted on the floor. The function of the dimmer switch, as the name shows, is to enable you to dim the headlamp beam from low to high or from high to low. It is really dangerous when you are driving with a bad headlamp dimmer switch, especially at dark environment. Here are some symptoms showing that your dimmer switch is failing: if the lights don't change between high and low beams and get stuck on one or the other; if the headlamps don't stay on high-beam setting, you need to stop driving and check it immediately to see if the replacement is necessary. Once you decide to change it, we are glad to offer you BMW genuine OEM headlamp dimmer switch with a discounted price.