Hi Kai,

Unfortunately, pdf datasheet here is all black !!!
Second, text on site (not datasheet) may not be accurate, because most of the PIR have a settling time of more than 60 sec, not 1-2 sec as mentioned.

I recommend,
1. Put a probe on ground track of PCB (with big track area / copper pour), and see where it leads, Black/Red or Brown, that takes care of ground.
2. You have a IC up there, check the IC's datacheet and find its Vcc, should be helpful in concluding +ve
3. Then use the third pin by assuming it as Op-Coll putput. (also try assuming it as NON-Open Coll o/p)

regards,
Anurag