2007 Suburban reverse/back-up assist works intermittently

My '07 Suburban back-up assist works 20% of the time I put the vehicle in reverse. The rest of the time the dash information center says...back-up assist disabled. When I push the button to activate it , the button indicator light blinks but nothing happens. I recently purchased the vehicle used w/44K on it.

You will need to get it on a engine/transmission/body capable scanner to test it out or to find the problem.
Post back any stored /past/present/history codes from transmission/engine computer.

If you have anything obstructing the sensors you will get that message. If thats not the case you may have a bad sensor.

Jeff