Travel sensor/Hall sensor

Brand new, directly from Chevy's former supplier's supplier. This is a solid state Hall sensor, also known as travel sensor. It comes with about 12" of wire and gets spliced directly into your wiring harness. The sensor clips into the rail of the aluminum cylinder housing. 

There are seven of these particular sensors in your top system. Used in Roof panel cylinders 89044556 (RH main lift cylinder - uses two travel sensors), 89044555 (RH stowage cover extension cylinder - uses two travel sensors), 89044554 (RH storage cover lift cylinder, uses one travel sensor) and latch cylinders 88980812 (LH and RH stowage cover lock cylinders - each uses one travel sensor).

These sensors detect whether the shaft on your cylinder is extended or retracted by measuring the permeability of the magnetic field nearby. They are more reliable than regular micro switches. The most common cause for failure is when someone or something pulls too hard on their wires. 

Before condemning the travel sensor itself, be sure that the wires routed to it are not shorting or broken in places where they flex a lot.