Inside your car are features many drivers spend years guessing about — until they accidentally press one of those mysterious buttons.
One day, I noticed three strange buttons on my rearview mirror and finally decided to figure out what they were for in my old car.
Honestly, I had never paid attention to them before. A mirror is a mirror — it hangs there and shows what’s behind you. What more do you need? But after repeatedly seeing online forum posts like, “What are the buttons under my mirror?” or “I pressed one and a light came on — is that normal?” I realized I didn’t really know the answer myself. So I started digging through owner discussions and advice from experienced drivers. Here’s what I found.
The first button most commonly mentioned activates the auto-dimming function. Many drivers admit they went years without realizing they even had it. The idea is simple: if a vehicle behind you is using high beams and causing glare, the mirror automatically darkens to reduce it. In older cars, drivers had to flip a small lever manually. With auto-dimming, the system handles it for you.
Using it is straightforward. Typically, you press the button once and a small indicator light turns on. From there, the electronics take over. Owners often recommend making sure the light sensor on the mirror isn’t blocked by a dash cam or dirt, since that can interfere with proper operation.
The second button is often linked to a built-in garage door or gate opener — essentially an integrated transmitter similar to a handheld remote. This feature is especially common in vehicles originally sold in the U.S. Many drivers say they didn’t understand why the button didn’t work at first. The reason? It needs to be programmed.
Setup usually involves holding the mirror button while positioning your original remote nearby so the system can learn the signal. Once programmed, the mirror stores the code. Drivers who use it often say it’s incredibly convenient — no need for a separate remote cluttering the visor or console.
The third button sparks the most confusion. Depending on the vehicle’s trim level, it could connect you to emergency services, link to a customer service center, activate a hands-free microphone, or enable voice control. In newer vehicles, it’s often part of an emergency assistance system that can automatically connect to an operator and transmit the car’s location.
Some drivers share stories of accidentally pressing it and being startled when a voice comes through the speakers. Others mention kids in the back seat “testing” it during a drive. In many systems, an operator first asks whether assistance is needed. If there’s no response, a welfare check may be initiated. The common advice from experienced owners: don’t press it out of curiosity — and read your owner’s manual first.
In simpler setups, that third button may just mute the microphone or activate voice commands, making it easier to place a call or enter navigation directions without taking your hands off the wheel. Drivers who finally try it often say they wish they’d used it sooner.
What’s most surprising is how many people drive for years without fully understanding their car’s features. Many buy used vehicles without manuals and end up figuring things out through trial and error.
In most cases, those three small buttons on your rearview mirror aren’t decorative. They typically control auto-dimming for nighttime comfort, a built-in transmitter for garage doors or gates, and a communication feature — whether emergency assistance or voice control.
Sometimes, it’s worth taking a closer look at the features you use every day. That small, overlooked button might actually make your drive safer and more convenient.