If a car's turn signal and DRL are separate, though, that doesn't mean it can necessarily keep its DRL on while signaling. It all depends on how close the two light sources are. In the "Spacing To ...

Hit the turn signal and you hear that soft click-click, the reassuring sound that your turn signal is flashing, of course, you have the light flashing as well, but you count on that sound. It’s a ...

Early vehicles used an old-school thermal style flasher to send current to the lights. The way this worked is, a bi-metallic spring would heat up as soon as you activated the turn signal.

On most modern cars, things work a bit differently. Manufacturers now use digital commands to flash the turn signal lights, so there's no actual mechanism to produce the clicking sound.