OBD Data port not working

Scan/Data port doesn't work nor does the cigarette lighter. But the auxiliary port right next to the lighter works. I checked the fuse box in the cabin and found fuse #3, 20 amp, was blown. I replaced the fuse and walked away. Time goes by and I find myself wanting to hook up my New Fixd Gadget. Put it onto the port and got nothing. Checked fuse and it was again blown. So,
First question, why would this #3 fuse blow if I have not used the cigarette lighter or the Scan port?
Second question, is there another link under my hood in the distribution box?
I downloaded the orientation of both fuse boxes, but neither one shows me that the side by side cigarette lighter and auxiliary port are separate from one another running on separate fuses. You see I’ve never not had power to my auxiliary port where I charge my phone and flashlights.