Most of the time it is a bad connection, or a blown fuse. If you have a test light or a volt meter, test the 2 amp fuse on the OBDII adapter plug to make sure there is power there, If there is, contact Tech Support for further troubleshooting. If not unplug the power wire barrel connector from the OBDII adapter and test the inside of the barrel for power. If there is, then the OBDII adapter will need replaced (part number: 40400-105). If there is no power inside the barrel connector, check the wire, and the connection at the fuse box.