Lenovo Thinkpad: T420 Drivers

However, if you have recently acquired a used T420 or performed a fresh install of Windows, you may notice that things aren't working quite right. The brightness keys don't respond, the Wi-Fi is spotty, or the battery life is abysmal. The solution is almost always driver-related.

If you are doing a clean install, download and install these in the following order: lenovo thinkpad t420 drivers