REAR ACCESS OPEN but it's not

[nrg8]

2008 Suburban LT started displaying REAR ACCESS OPEN, interior lights come on, open and close the rear hatch message goes away. Drive for a while, no set pattern or time frame, comes back on. Where do I start?

 

[nrg8]

so this is what I found

Took apart interior panels, the glass latch was loaded with dust, and the 12 pt bolts securing said latch, had backed themselves out. I guess this was a previous issue and was adjusted, but the bolts were not tight, just snug. So I found the original witness marks and put the latch back to the spot it need to be. The latch does have a micro switch in it, and mine looked to have been lubed up and the grime collected in the latch housing. It cause the switch to not have free movement, got some electrical contact cleaner sprayed in, and blew the gunk out. All is well now