I work for a GPS company and we have devices that plug into the OBDII port on vehicles. In troubleshooting these during installation we have found that some individuals do not have power to the OBDII port. In several manufacturers I have found the OBDII's power to run through the same fuse as the cigarette lighter (mainly in Ford). I would check your fuses again, but like Eddie said haven't heard of this happening in the Jeep before, nor do I know if or what fuse it is linked to specifically.