Problems with Ford F250 Diesel 2006 Alarm

I have a 2006 F250 with a 791XV in it.  Whenever I arm the alarm about 15 seconds later it goes off saying a door is open when they are not.  I have checked all the doors and they are closed as well as the dome light turned off correctly.  I grabbed all four doors at the gem module and diode isolated each one.  Any ideas?  I am wondering if for some reason the gem module is backfeeding now into the alarm.  What is strange is that it didn't do it at first for a couple of weeks and I don't get a secondary chirp when arming but always goes off about 15 seconds later.

On each door pin wire, put a diode in line with the cathode facing AWAY from the BCM. THEN in FRONT of those diodes put 4 more diodes, with the cathode end facing AWAY from the remote start. Then hook to the R/S alarm.

On Super Duty Fords, I've been using the dome light wire......BLACK/ blue, positive trigger, passenger kick panel......it doesn't seem to cause false alarms like some of the other Fords do.

True...but make sure you don't turn off the dome light with the switch......no door trigger!