The BTR/DSI/ION 4spd Auto transmissions are most definitely NOT sealed.
Of course you can check.
The filler plug, is a 16mm nut on the right hand side of the transmission towards the back.
Make sure you only use a six sided socket, (not a 12 sided) or you'll likely round off the plug hex.
The fluid should be a clean cherry red colour.
If it's a black/red, or brown colour, then it needs a service.
Only use TQ95 transmission fluid in BTR's.