The USB ports on a Vizio TV serve a number of different purposes. The port functions vary across different TV models and some are used for diagnostic testing while others are intended for linking exterior devices via USB connections and cords. Some models come with multiple USB ports and each has a specific purpose. You may try connecting an exterior hard drive to one port for example but it does not work because that port is only made to accept an external keyboard. You must determine the use for each port before attempting to connect a device.
Service Port on TV
The Vizio TV USB port or ports on older models are often only intended for running service diagnostics. This especially applies to models made before 2010. They are not usable unless you have the equipment to test the TV and scan for error codes. Some electronic stores will have the capability to scan the TV through the USB port but many of the older TV sets are becoming obsolete as they are replaced by smart television sets. Newer models may also have a service port along with one or more other ports for media purposes.
Vizio USB Input
To determine the function of each Vizio USB input, consult your television owner manual. Not all Vizio televisions share the same functions and the purposes of different USB ports are dependent on the television model. The television will often have a port that can handle external controls like a keyboard or mouse. Other USB ports are used to connect external media devices like an Amazon Firestick. You can also connect an external drive that holds video or music files. Connect and open the drive to access and play these media files.
Streaming through an Amazon Fire Stick or Apple TV is easy using the USB connection. You can also connect a phone or tablet to the TV through a USB port and stream movies and media saved to your phone. This makes it easy to connect apps like Netflix and Amazon Prime while playing movies downloaded on your phone. You will still control the volume through the television speakers but the media is controlled on the phone or tablet. It turns any Vizio television into an instant extension of your telephone without downloading any apps to the television directly. However, Vizio smart TV sets do make it easy to install apps and connect all of your accounts. Running the television through a Wi-Fi connection will save your phone data and make regular viewing easy.