It’s in the event your EZ-Pass Transponder isn’t read by the toll gantry, it will take a picture of your license plate instead and will later match it to your SunPass/E-Pass/EZ-Pass account. If traveling on a FTE/Sunpass maintained road (like the FL-Turnpike or SR-528 west of McCoy Road), they have indicators next some of the toll booths that will glow “SUNPASS, GO” to let you know it picked up the transponder. If on CFX/E-Pass maintained roads (like 417, 408, 429), these indicators were removed these several years ago so there is no way to know if it picked up your transponder or not (CFX also automatically takes a picture of every license plate that goes through so you will see it flash at night).