Turn Signal (Indicator, Blinker)

They are fitted at the front, rear and often on the side mirrors. Fast flashing usually means a bulb has failed. A light tap often gives three flashes for lane changes. LED conversions may need load resistors or coding so the car does not show a bulb failure.

A relay or lighting control module switches the lamps on and off at a set frequency.

Replace failed bulbs promptly, because other drivers rely on the signal. Signal in good time before turning or changing lanes.