What is the secret button on the rear view mirror?
There isn’t a universal secret button on rear-view mirrors. In most cars, the button people notice on the mirror housing is either for HomeLink garage-door operation, for dimming the mirror, or for emergency/assistance services depending on the model.
Common mirror button categories
Below are the most common types you might encounter on rear-view mirrors, but availability varies by make and model.
- HomeLink or other remote opener controls (for garage doors, gates, and compatible devices)
- Auto-dimming control (toggle to turn dimming on or off)
- Display toggle for digital compass and interior temperature
- Emergency or telematics button (for assistance services, such as OnStar or similar), often color-coded
Not every car has all of these, and some may place them in different areas or combine them with other mirror features.
How to identify the button in your car
Since the exact function depends on the model, here’s how to determine it and use it safely.
- Look at the mirror housing for symbols or labels (a house icon for HomeLink, a sun-like icon for dimming, a compass, or a colored emergency button).
- Consult your owner's manual or the manufacturer's website for model-specific diagrams and instructions.
- If you suspect HomeLink, follow the standard programming sequence: hold the remote near the mirror, press and hold the HomeLink button until the LED changes, then press the remote’s button to program. Test to confirm it operates the device.
- To test or adjust auto-dimming, try driving at night behind glare-producing headlights and see if the mirror dims; use the OFF or DIM button to switch modes if available.
Following these steps should help you determine the exact function of the button in your vehicle and avoid accidental presses.
Emergency and telematics buttons: what to know
Some models include a dedicated emergency or telematics button on or near the mirror housing. These are intended for urgent assistance and connect you to a service center or dispatcher. Use them only in genuine emergencies or as directed by your vehicle’s owner’s manual.
Summary
The so-called secret button on a rear-view mirror isn’t a single feature shared by all cars. Most often it’s one of a few standard controls—usually a HomeLink garage-door opener, an auto-dimming control, a display toggle for a compass/temperature readout, or an emergency/telematics button. To know which one yours is, check the mirror for icons, read the owner’s manual, or ask a dealer for model-specific guidance. Always use any telematics or emergency button as intended by the manufacturer.
