Help, nav installed--changes sources when put in gear

[dillpicklelsu]

I bought a nav unit out of a 2010 truck(not sure which one exactly) to put in my 2011 yukon. I had a dealer install a backup camera and the nav unit. The told me that there was an issue with it changing sources automatically, but they blamed it on the disc. I investigated the problem, and removed the disc and even tried unplugging the VSS wire. In park the unit works fine. When it is put into drive it starts changing sources automatically and if I turn it off it turns itself back on. I called a certified radio repair shop and explained the issue and they said that the radio is not broken. They think maybe there is an issue with the parking brake wire? Can anyone help??

 

[jcrack_corn]

sounds like the radio is broken.