If you’re like half the drivers on the road, and we hope you’re not, the description of a BMW Turn Signal should read “the thing I never use.” But, since we’ll assume you’re a courteous driver, our explanation will be a bit more in-depth. The BMW turn signal is a circuit in your lighting system that consists of a switch, a flasher, and a bulb at either end of the car. The switch and bulb are self-explanatory. The flasher is what rapidly connects and disconnects the BMW turn signal circuit to make the light flash.

If you’ve got turn signal problems, the bulbs are the first things to check. And not just the filaments—check to make sure the BMW turn signal bulbs are fully seated and that they have good ground connections. The flasher, and then the switch, in that order, are the other most common causes of BMW turn signal problems, so if you check those three places you’ll most likely find the source of your troubles.