2007 Chevy Suburban service rear park assist message

Have it scanned for dtc's, it too hard to diagnose without a code, on these A fault anywhere on the circuit or in any single sensor will affect all of the sensors. These sensors are wired in a series parallel. When testing it should have 8-9 volt reference. Its easier to use a scan tool and switch sensors with different locations and see if the dtc sets on a different location, post back with the code.