Five second beep when opening tailgate (95 FZJ80)

[shishkabobs]

The past couple days I've noticed when opening the tailgate there's a 5 second beep coming from the dash that I've never heard before. It sounds like the same beep that's made when leaving your keys in the ignition while opening the door and the like. There are no current issues with the central locking system or alarm from what I can tell.

Is this normal behavior? If not, any suggestions on what could be the issue?

 

[mct75]

Sunroof open?

 

[shishkabobs]

No, double checked that and it is closed.

 

[skhochay]

under the dash or alarm buz ?

 

[shishkabobs]

Under the dash, just like when leaving the keys in the ignition and opening the door.