I have a problem with the rear blind control. I checked all fuses and relay. I pull the panel off to test the shade button nothing available . There are three plug-ins on the back of the panel. I have only two being used. The one directly behind the blind button is empty. I find it no wire plug in for it. Am I missing a part of my wiring or is the plug in for phone option? Blinds in the up position, it’s intact. Please advise what I’m missing. I can’ find a harness schematic or routing information for this system.