Signs of a Faulty Vehicle Speed Sensor: How to Identify Potential Issues. In the realm of automotive diagnostics, one of the most common problems that drivers encounter is a faulty vehicle speed sensor. This crucial component, also known as a VSS, plays a pivotal role in ensuring the accurate functioning of various systems within a vehicle. Once you locate it, make sure the car is rested for like an hour. Because you need to cool down your car before you start cleaning the speed sensor. So, once it cools down, take a cloth and wipe the sensor gently. Keep the cloth dry fast when you are rubbing it. And then clean the speed sensor by a damp cloth. When the speed sensor fails, this can impact your speedometer operation – and other components. For instance, the transmission control system and engine will not be able to make the right adjustments to ensure the efficient performance of your vehicle. So, when you have speed sensor problems, this can be a safety risk for your vehicle. Hi speedo not working on 638 1:take off n/s front wheel look frow the wheel arch on the top of the gearbox see pics. 2:undo the 10mm bolt pull out the sensor cut the wire adout 12 inches up, open up the wire up one brown wire one white wire strip ends see pics. 3:connect new sensor wires brown to brown white to white. Defective vehicle speed sensors can cause many problems in the computer output control systems. Speed is used by the control module as an input for many systems. If the input is bad the output will not be good either. Examples: defective vehicle speed sensors may cause improper torque converter clutch lockup as well as a cruise control Disconnect the vehicle’s battery to prevent electrical issues during the replacement. Locate the Sensors: The Input Speed Sensor (ISS) is usually located on the front of the transmission case near the input shaft. The Output Speed Sensor (OSS) is typically found on the rear of the transmission, near the output shaft. Failure Date: 05/13/2020. Vehicle was diagnosed with having a left rear speed sensor and speed sensor wire was broken due to a piece of plastic part came separated from the wheel. Have all kinds of lights come on dashboard and flash on and off, until sensor is replaced with new at an astronomical rate, which cannot be replaced at this time. Turn the ignition switch ON while holding the odometer/trip meter switch for 5 - 8 seconds to enter self diagnosis mode. The odometer/trip meter will display tESt in self diagnosis mode. Keep pressing the odometer/trip meter switch until you reach 0000, it should be a few more clicks after GAGE. Step 1 – Lift vehicle and remove wheel (s) In order to easily access the wheel speed sensors, it is best to lift the vehicle with a floor jack and support it with jack stands. Additionally, if replacing a front wheel speed sensor, the wheel will need to be removed. Use your 17mm socket and impact gun here. The rear wheel speed sensors can be Erratic or Inaccurate Speedometer Reading. As we mentioned earlier, one of the most common signs of a bad speed sensor is an erratic or inaccurate speedometer reading. If your speedometer is constantly jumping up and down, or if it’s not reading the correct speed, there’s a good chance that your speed sensor is bad. RTM5nx.