I'm a gm technician and i just actually did this to a 2013 sonic but it was not just plug and play if you wanted to do it here is what i had to do
first you need to check the part number on your radio in 2013 they offered two choices both with uf7 options but the one that ends in (2050) which may cross over from a lower part number did not have the circuts internaly to run the camera. and the part number ending in (9008) which does have the capibilty.
in the sonic i did which was a 2013 w uf7 radio 2050 we had to swap out the radio first with a 9008 which will run you about 500 dollars
then we had to buy a pigtail (basically a connector for the backupcamera with wires already in it so you can wire it in yourself) remove the trunk trim and harness and install the pigtail with wiring leads through the hatch which was not easy there are 5 wires you need from this 2 video signals, a ignition power, a ground, and reverse signal
for the two video signals you have no choice you have to get two terminated leads (basically wires with pins you can install in the connector) and put them in the radio connector pins 7 and 8 and then add wire and run to through the trim into the hatch.
for ignition power i used c202 pin 35 which is a fused ignition wire that does nothing like a spare the wire comes into connector 202 but goes no where so this was an obvious choice i splced into the wire at the connector
for a ground wire the harness for the trunk has 2 large black wires that go to the ground that would have been used if the camera was already installed so i just patched into the ground in the trunk harness
and for a reverse signal i just ran a wire from the left rear tail lamp to the interior through the trunk harness to my pigtail connector
it can be done its not a job for amatures though it take substantial understanding of wiring and probaly sum total with parts labor cost about 1000 dollars
