https://phys.org/news/2019-01-china-yutu-rover-side-moon.html

The mission's various scientific payloads were also checked and verified before the rover took to the surface. This included the three radio antennas, which were deployed at 04:00 pm Beijing time on Jan. 4th (03:00 am EDT; 12:00 am PDT on Jan. 3rd). They then established an uplink with the relay satellite (Queqiao) that will allow the lander and rover to communicate with mission controllers on Earth.

The controllers also took the time to deploy the rover's solar panels and verify that the mission's scientific payload (altogether, seven instruments and cameras) were all in working order. In addition to the instruments inherited from the Chang'e-3 mission there's also three new instruments that are the result of international collaborations.