* Indicator Switch: This is the stalk on the steering column you use to activate the left or right turn signal. It's a simple switch that completes a circuit.
* Flashing Relay: This is the brains of the operation. It's an electronic switch that rapidly interrupts the circuit, causing the lights to flash. Older systems used electromechanical relays that employed a bimetallic strip that heated and cooled, causing the contacts to open and close. Modern cars often use electronic solid-state relays which are more reliable and quieter.
* Indicator Lamps: These are the bulbs (nowadays often LEDs) in the front and rear of the car that illuminate.
* Wiring Harness: This provides the electrical connections between all the components.
How it works:
1. Activation: When you activate the indicator switch (left or right), it closes a circuit leading to the corresponding side's indicator lamps and the flashing relay.
2. Relay Operation: The relay receives power. In an electromechanical relay, the current flow through the coil heats the bimetallic strip, causing it to bend and open the circuit, cutting off the power to the lamps. As the strip cools, it springs back, closing the circuit again, and the process repeats itself, creating the flashing effect. Solid-state relays use transistors to achieve the same rapid on/off switching.
3. Light Flashing: The rapid on-off switching of the relay causes the indicator lamps to flash at a specific rate (usually around 60 to 120 flashes per minute), which is regulated by the relay itself.
4. Hazard Warning Lights: A separate switch activates the hazard warning lights, which simultaneously engages both the left and right indicator circuits, making all indicators flash together. This usually bypasses the normal relay mechanism and uses a dedicated flasher unit for simultaneous flashing.
In short, the indicator switch initiates the process, the flashing relay creates the flashing action, and the indicator lamps provide the visual signal. The whole system relies on a controlled interruption of the electrical current to create the characteristic flashing pattern.
