Keyless Entry Keypad
WARNING: This page is about a different car, the 2018 Ford F-550 Super Duty, 2018 Ford F-450 Super Duty, 2018 Ford F-350 Super Duty, and 2018 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
When a button is pressed on the keypad, it provides a ground signal to the corresponding voltage reference circuit(s) to the BCM.