My girlfriend has an 07 1500 new body style LTZ. It has the rear park assist and was working just fine before. Now when you put it in reverse the system makes the single beep. Then as you back up the lights in the back window on the passenger side all seem to work. The only problem is it doesn't beep anymore. As you get closer the beeps get more should get more and more frequent the closer you get to something. Anyone have this issue before? Any ideas how to fix it? I tried turning it on and off, but no luck. Thanks.