Stupid question, but did you replace the fuse? I used to have one of those cars and when I bought it I plugged a scanner into the OBD2 port and there was no power to it, and I checked the fuses and was about to say nevermind and leave, and I decided to try swapping the (still good) fuse with another one of the same kind in the fusebox and it worked fine the rest of the time I had it.