flasherrelé

A flasher relay is an electromechanical or electronic device in motor vehicle electrical systems that controls the blinking of turn signal and indicator lamps. It acts as a timed switch, repeatedly connecting and disconnecting the lamp circuit to create the characteristic blink.

Traditional flasher relays are thermal devices. Current through an internal heating element warms a bi-metallic strip, which then bends and opens the circuit. When the strip cools, the circuit closes again and the cycle repeats. The resulting blink rate depends on the supply voltage, ambient temperature, and the electrical load (the number and type of lamps).

Electronic flasher relays use an oscillator and a switching element to produce pulses. They offer more precise control of blink rate and can better accommodate varying loads. Some electronic units include load sensing and adaptive timing to maintain a consistent rate, even with different bulb configurations. Modern vehicles may utilize a single unit for both turn signals and hazard lights, or integrate the function into a body control module, reducing or removing a separate relay.

Load considerations are a common design issue. Conventional flashers assume a defined load, so when a bulb is burned out or when LED bulbs are used without resistors, the blink rate can change or the lamps may not flash correctly. To address this, LED-optimized flashers or load resistors are used, and some vehicles rely on electronic control modules with built-in flash logic.

Common failure modes include loss of flashing, excessively fast flashing (hyper-flash), or signs of poor contact. Replacement with the correct type for the vehicle and load, or using LED-compatible units, is typical maintenance.