Thank you for your reply, there are some new discoveries about this bass, I found the stamp on the neck (see picture). I also realized the problem with the active pickups, I suspect that the previous owner (or a certain owner) changed a lot of wiring including the battery box when he replaced...
The seller says this bass is from 1994, I have played it for over a year, I think this bass is genuine but I am not a professional guy, I would really like to know what do you guys think!
Some info:
One of the pickups was modified before I bought it.
I don't know how many owners it has had...