I have used a TriggerBox with the defaultActivateSelfTRIG script applied on it, to trigger certain traps in my dungeon. However, when I go ingame, and enter the trigger box, the trap only activate for a second or so, before stopping to function.

Examples:
-The swing blades found in nordic ruins only do ONE swing after being triggered, and then stop.
-The dwemer fire trap activates, sprays fire for a split second, before retracting into the ground again...

Why does this happen? Why won't the traps keep functioning? Is there a property in need of adjustment, or should I use an entirely different script instead?

Thx in advance!

Double click on your trigger to bring up the object reference window. Scroll to the right untill you see the 'scripts' tab.

In that tab select your script and click the 'properties' button. There is a property named 'doOnce' , by default this is TRUE. set it to FALSE and your trap should fire every time the player enters the trigger.

It still doesn't work :/ The flame pillar go up from the floor, only to immediately lower itself down again.

wait, be more specific.
I can't tell if your problem is that the flame pillar doesn't go up after you step on the trigger again (which it should if you implemented my suggested fix), or if you expect the flame pillar to be up constantly while the player is on the trigger.

If you expect a 'constant flame' the issue is that you probably want a different trigger script

Okay sorry, I might have been too unspecific.

I want the following to happen: when I enter the trigger, I want the flame pillar to activate, and keep being activated even when I have left the trigger (if that is possible). I want the same to apply to the swing blades.

Yeah, you want to use a different trigger script then.
You want to use 'PressurePlate' as your trigger. When the player steps on it the trigger the trap should fire continuously.

Okay thanks! Can this script be applied on a trigger box as well, instead of a plate?

yeah, it's just a script. When you click the button to create a trigger volume, it will ask you what trigger script to use, just select 'PressurePlate'
PressurePlate is just the name of the script, it can be placed on any trigger.