I'm not sure about the GD (other GD owners can chime in). Nabenta na kasi namin yung GD.

But on my Patrol, the door ajar warning also doesn't work with the key cylinder in the OFF position. The dome lamps still turn on when set in the DOOR position but the dash lamp doesn't illuminate. And that is the OEM set up even before any work was done on my vehicle.

Not also sure about the rear doors. But that is how our former Volvo also worked (it had a more expensive Autopage system). The system cannot detect the tailgate as it uses a different wiring harness from the other doors.

Better to have it checked with Jemson na lang to be sure.

Better also to ask him if he put in the ignition kill. One sure way to test it is to arm the alarm, open doors manually (siren will sound) then try to start the vehicle. If car doesn't start, you have ignition kill.