What is the light that blinks in car?
The blinking light is the turn signal indicator—the exterior blinkers that signal a left or right turn, with a matching dashboard indicator that mirrors the action.
In this article, we explore what these signals are, how they work, and what to do if one isn’t functioning correctly.
What triggers the blinking lights
These signals exist to communicate your driving intentions to other road users. Exterior amber lights mounted at the corners flash on and off to indicate a planned move, while a corresponding dashboard icon confirms the action for the driver.
- Left turn signal lights flash on the front and rear left corners, signaling a left turn or lane change to the left.
- Right turn signal lights flash on the front and rear right corners, signaling a right turn or lane change to the right.
- Hazard lights flash all four corners simultaneously, signaling an all-around warning or emergency situation.
- In some designs, side repeaters or additional lights may blink in sync with the main signals for added visibility.
Exterior signals are designed to be visible in daylight and at night, using bulbs or LEDs to make the pattern obvious to other drivers and pedestrians.
How the blinking is generated
Older cars used a mechanical flasher relay that breaks and makes the circuit to the bulbs at a steady rate. Modern vehicles rely on electronic control modules that manage timing, and can adjust the blink rate based on electrical load or other vehicle data. When you activate a signal, the module repeatedly powers and then cuts power to the chosen circuit, creating the blink. The hazard switch engages all four corners, typically overriding the individual turn signals.
Mechanical vs. electronic systems
A traditional flasher relay is a small device that opens and closes contacts in rhythm, producing the telltale click and the blinking sequence. In newer cars, a body control module or dedicated signaller handles timing more precisely and can compensate for LED loads, traffic conditions, and vehicle speed. LED setups often require load resistors or dedicated LED flasher logic to maintain a consistent blink rate.
Dashboard indicators
The driver’s information cluster often mirrors the exterior signals with blinking arrows for the chosen direction. In addition to confirming your signal, the dashboard indicator helps point out a problem if you notice one side isn’t flashing or if the rate changes unexpectedly.
- Left turn indicator on the dashboard mirrors the exterior left signal with a blinking left-arrow icon.
- Right turn indicator mirrors the exterior right signal with a blinking right-arrow icon.
- Hazard status is shown by a blinking hazard icon, and in many cars the dashboard arrows will flash in sync with the exterior lamps.
- A rapidly flashing indicator, or "hyperflash," often signals a bulb or fuse issue and should be checked promptly.
Dashboard indicators are especially helpful if a bulb burns out or a light is obscured, allowing drivers to respond and drive safely.
What to do if a signal stops blinking
If a turn signal or hazard light stops blinking, start with the basics: check for burned-out bulbs, inspect fuses, and verify the relay or control module’s function. For LED installations, ensure proper resistors or controller settings are in place to prevent abnormal blinking.
Summary
The blinking light in a car is the turn signal indicator, which alerts other drivers to your intended movement. Exterior blinker lamps and the matching dashboard indicators work together, controlled by a flasher relay or electronic module. A healthy system blinks at a steady rate and remains in sync between exterior lights and dashboard icons. If the signal fails or blinks abnormally, check bulbs, fuses, and the signaling module, and consult a professional if needed.
