How to Check Speedometer Calibration

How to Check Speedometer Calibration

Instrument clusters, like all other components in a vehicle, can get damaged or become faulty over time without you even noticing at first. The best thing that you could do is make periodical assessments of your instrument cluster to see that everything is working the way it should be. You may be reading this and thinking to yourself, “That sounds like a good idea but I have no idea how to check speedometer calibration”. Fortunately for you, I will precisely tell you how to check speedometer calibration in your vehicle. After following what I tell you, you will hopefully know how to tell if there is anything amiss with your speedometer in the future.

To begin with, you will be pleased to learn that you don’t need any fancy recalibration device to check if your speedometer is working. Rather, you just need some time, patience, a stopwatch, a car, and an extra set of hands.

A quick and easy way to check the accuracy of your speedometer is as follows. First, find a part of a highway that has visible mile markers. Drive at a constant speed and have your front seat passenger collect and record all data. You will want your passenger to time how long it will take for you to travel one mile. You’ll want to proceed with dividing 3,600 by the time it took you in seconds to drive that one mile. The answer to this equation will be your actual speed reading. Therefore, if you put your car in cruise control at 60 mph and complete the mile in 50 seconds, your real speed will be 72 mph. Not only is that enough to get you pulled over, but it will also tell you that your speedometer reading is 20% lower than it is intended to be. Of course, the percentage may be a little off due to the margin of error caused by stopping the stopwatch—but nevertheless it should give you a rough estimate on the amount that your instrument cluster is off by.

If the percentage is way off from what it should be, you might want to send the unit in to a professional. The company Safety Restore specializes in instrument cluster gauges repair and will be able to recalibrate your speedometer—and for a very affordable price at that!