Need help troubleshooting an unknown zone

Working on my 2nd konnected setup. 

It had 6 zones, nothing was labeled, and the keypad showed that Zone 5 was triggered.

So I've got it swapped out, and just did a direct mapping of the existing zones, and now know which zone goes to which door/window sensors. Except for the problematic Zone 5. No windows or doors triggered it. It's also triggering on/off without a clear cause. It's just a red/black wire (no aux), nor was it crimped together with anything else, and no resistors. Other than the door/window sensors, the system has the 4 keypad wires and the siren. No motions sensor or glass breaks, which i think require aux power. Would a garage door have a zone?

Its worth noting that there is one set of windows that don't trigger anything either. So my current assumption is they are Zone 5. I checked the window sensors, and don't see anything suspicious. Only problem is they just remain close and don't seem to have any correlation to when Zone 5 triggers on/off. 

Anyway, could use some suggestions on how to debug this.


Oh boy, this can be frustrating, and I have a similar issue.  Since everything pretty much works of simple continuity, you will need to isolate that window sensor, possibly trying to get at the contacts that go into the sensor.  The fact that everything else is wired and working, and you have this one mystery zone, I have one as well but the wires were not even connected.  It would have been zone 6 for me, as zone 7 and 8 had connections and only 6 was not connected.  I have to figure out what those wires go to.  

Maybe a secret door to hidden treasures, who knows.  If I have learned anything going through this, it is frustrating to work behind alarm installers.  In my previous house, they twisted wires at one of the sensor locations, because I guess the tech either did not have spare sensors or during trouble shooting, never went back and hooked the sensor up.  Both the switch and magnet were installed though with the double sided tape.