The speed sensor in a 2007 Jeep Grand Cherokee can be tracked down on the result shaft from the transmission on the right back side of it. This sensor is quite simple to recognize in light of the fact that it is the main sensor with a wire coming to it that is close to Your driveshaft. The speed sensor estimates the rotational speed of Your driveshaft and transfers that data to the ECU. The ECU is then ready to ascertain the speed that You are driving at in light of that data and will let you know that at Your speedometer on the scramble. On the off chance that Your speedometer isn't working right then the most probable guilty party is the speed sensor.