Let me know about the door wiring and I will reply back with the next possible item to check or the most likely cause.
I believe that the most likely cause will be related to one of the door ajar switches. If the switch is causing the issue than the interior light would stay on and the alarm will not arm either.
There are 5 switches total. One on each of the side doors and one on the rear liftgate.
I recommend removing each door switch one at a time and ground the wire going to it and see if the interior lamp eventualluy goes off. If you locate a switch that eventually turns the light of then you can try to adjust the switch or replace it.
Check the 4 switches and let me know what you find. Dont check the rear hatch at this time.
I believe that I read the switch operation incorrectly. I need for you to disconnect each one and pay attention to the light to see if any change. If still no change and the switches check okay then your next step is to use a scanner. A simple code reader will not work, they only access the engine controller. You will need either a high dollar scanner or the factory DRBIII scanner. Then you will ned to access the theft system in the Body control module. Also make sure to check the other modules to make sure there are no other related codes related to the situation. Otherwise there isnt anythign else you can check at this point with out the scanner.
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