There is a data link connector (DLC) in every OBD2 vehicle that allows access to the vehicle’s on-board computer. This 16-pin connector is always located inside the front dashboard of your vehicle. The connector looks like this:

There are nine standard places where it may be located. The location varies by year, make and model, with the most common locations just under the steering column by the driver’s knee.

The head of the CarMD handheld tester is designed to plug into the DLC connector. There is only one correct way to plug in the device. Please note that on some vehicles the connector upside down, so your tool's screen my be facing down.