Keyless Entry Transmitters
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2015 GMC Yukon XL, 2015 GMC Yukon, 2015 Chevrolet Tahoe, 2015 Chevrolet Suburban, and 2015 Cadillac Escalade ESV. However, it is still accessible from the selected car via links, so may be relevant.
By operating any of the exterior door handle buttons, a nearby transmitter is challenged by a keyless entry antenna. The transmitter will send an RF response to the remote control door lock receiver, which communicates with the BCM. The BCM will interpret this communication and either allow entry into the vehicle or deny it.