Did you know that you can get a ticket for a malfunctioning speedometer? Not only would you be risking a speeding ticket with an inaccurate speed reading, but you can get charged for both offenses -- harsh! A speedometer on all vehicles is an important safety feature susceptible to breaking or falling out of calibration. Most speedometer problems lie within the speedometer cable or housing.
The majority of speedometers in our vehicles today are electric. The speedometer cable is fastened to a gear inside the transmission or driveshaft. This cable tracks the rotation through electrical vibrations then translates the duration of the electrical signal into the speed when you are driving. A secondary speedometer cable is connected to a wheel sensor and measures the distance at which your vehicle travels. The speedometer cable sends all this data to the instrument panel and then delivers the information to the speedometer.
On the other hand, the cable housing is a protective cover surrounding the cable to prevent it from being damaged. These two components work simultaneously to power the speedometer and give drivers precise reading. Over time, the components can fail due to damage or typical wear and tear. Here are several warning symptoms that may indicate a failing speedometer cable or housing:
1. The speedometer Does Not Move At All. If the pointer on your speedometer does not budge during acceleration, it's plausible that the speedometer cable and housing have already failed. Nevertheless, this problem may also be caused by an electrical misconnection.
2. Speedometer Needle Jumps and Skips. Suppose you see that the needle on the speedometer jumps quickly from a smaller number to a large number (55 to 65). You may even hear a squealing sound coupled with the sudden movements of the needle. In this case, the speedometer cable is most likely damaged, or the sensors on the transmission are not accurately sending the proper signal. Your speedometer needle should move slowly and progressively as you accelerate and decelerate.
3. Squealing Noises. The unusual noise you may hear is often correlated with the speedometer needle jumping around erratically.