How to Tell if Your Signal Lights Are Going Out

If there’s anything worse than being the guy who proceeds down the road with a turn signal unknowingly flashing, it’s someone who doesn’t use a turn signal at all. Making sure your indicator lights are in good repair is part of responsible car maintenance. Is there a way to tell if your signal lights are going out?

What your turn signals are trying to tell you

Headlight and signal lights on a white 2022 Toyota Corolla Cross
Headlight and signal lights | Toyota Motor Sales, U.S.A., Inc.

One way to tell if your turn signals aren’t working is to notice the hand gestures of other drivers. According to GoAuto, A better way is to pay attention to the rhythm of the signals. If and when your turn signals start to blink faster, you’ve probably got a burnt-out bulb.

That’s not the only way a turn signal can tell you it’s time to be balanced. According to CarFromJapan, a signal flashing too fast or too slow may mean various things. One possibility is a loose signal switch connection, or the headlamps are poorly powered or ungrounded. A faster flashing may indicate the alternator is overcharging the battery, while a slower than normal flashing may mean the alternator is undercharging the battery.

If your turn signals aren’t working right, don’t panic. Most turn signal issues are easy to fix.

A brief history of automotive turn signal lights

Cars were invented long before automatic turn signals. Before the safety devices, motorists alerted other drivers by using the same hand signals used by bicyclists.

Anyone intending to turn left indicated so with their left arm held straight out the driver side window, perhaps with a pointed finger. Drivers intending to turn right held the same arm, bent at a 90-degree angle, out the same window. As with bicycles, a car driver slowing down to a stop held their left arm at a downward 90-degree angle.

As far as the history of the turning signal, there seems to be some controversy regarding who actually invented the automotive turn signal. History Garage says Percy Douglas-Hamilton submitted the first patent for a turn indicator in 1907. However, his design was never implemented, as far as we know.

Car Talk explains that Biograph silent movie actor Florence Lawrence came up with something she called an “auto-signaling arm” that would be attached to a rear fender and could be lowered or raised by way of electrical push buttons that activated with the brake pedal. Lawrence failed to patent her idea. Interestingly, her mother, Charlotte Bridgewood, invented and patented one of the first automatic windshield wipers in 1917.

In the late 1930s, Joseph Bell patented the first flashing light turn signal. The safety device Bell called the “Flash-Way Directional Signal” was incorporated into the 1938 Buick but did not become a commonplace automotive feature until the early 1950s.

Fascinating facts about the turn signal sound

Until the 1990s, automotive turn signals operated by an electrical current passed through a spring made of two metals that heated at different rates. This difference caused the spring to bend in a way that completed the circuit and sent a pulse of electricity to the outside-mounted indicator light. That pulse popped the spring into position and made the distinctive clicking sound of a turn signal in older vehicles.

Most cars and trucks made since the early 1990s contain an electronic relay system that operates left and right turn signals with an electromagnet and a microchip. The relay completes the circuit for repeated split seconds as with older signals. Although not technically needed to function, many car makers add a bimetallic spring to provide the familiar click-click-click blinker sound that drivers have become accustomed to. According to North Carolina-based Quality Plus Automotive Service, cars made in the 21st century offer that same satisfying sound purely with electronics.

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