The transmission sensor of a vehicle is generally located directly below the actual transmission of the vehicle, which is usually positioned on the underside of the vehicle. The sensor could also be placed on the rear sides of the vehicle's transmission.
In order to actually reach the transmission of a car, it must be lifted above ground level, usually by the front end of the vehicle. A floor jack is the best method to achieve this. The sensor itself appears as a small plug on the transmission. It sometimes appears as a small magnetic coil. The sensor is also attached to an electrical chord.