Car Talk

Reason Why Your Speedometer is Not Working – Diagnosis and Fixes

Avatar Adie Tinkle -

Have you ever found yourself in a situation when you are moving down the road, and suddenly, you notice that your speedometer is not working? It is a common issue that can leave you concerned and worried about your vehicle’s health.

A speedometer helps you find out how fast your vehicle is moving. If it’s not working properly, it can get you into legal trouble and, in the worst scenario, even lead to an accident.

Fixing the speedometer can either be extremely simple and cheap or a complicated and costly job.

Let’s talk about the working of speedometers, common causes and symptoms related to speedometer issues, and how we can diagnose and troubleshoot the issue.

What is the Role of a Speedometer?

A speedometer is a crucial component in a vehicle’s dashboard that shows the speed at which the vehicle is running. Real-time information about the speed of the vehicle helps the driver move the vehicle in adherence to speed limits and ensures safe driving conditions.

A speedometer is installed in vehicles in analog or digital formats, with the analog version featuring a rotating needle and the digital one showing the speed of the vehicle numerically.

Reasons Behind Speedometer Not Working

Speedometers can stop working for various reasons, and knowing the original cause behind this is crucial for ensuring a safe and smooth driving experience. 

Here are some of the primary reasons why your speedometer might stop working:

  1. Fault in Connectors and Wirings

Electric problems with connectors and wiring that connect the speed sensor to the speedometer can affect the signal transmission. Damaged and corroded wires, blown fuses, and loose connections can all lead to speedometer issues.

  1. Speed Sensor Issue

Speed sensors, both mechanical and electric, can fail and become damaged over time. In the case of the mechanical speedometer, the cable might be worn out or broken, while the electronic speed sensors can accumulate debris and malfunction.

  1. Sensor calibration issue

When you make modifications in the gear ratio, transmission, or vehicle’s tire size, the speedometer requires calibrations or reprogramming.

  1. Vehicle Computer Problems

Modern vehicles use onboard computers like the Engine Control Module (ECM) to calculate and transmit speed data. Issues like glitches can affect the speedometer’s performance.

  1. Gearbox Problem with Speedometer

In older models, a mechanical gearbox is present that connects the speedometer to the transmission. If the gearbox is damaged, it can cause speedometer inaccuracies.

  1. Environmental Issues

Extreme temperatures, exposure to the elements, and moisture can cause damage to the speedometer over time.

  1. Wear and Tear as a Result of Excessive Mileage

The components of a speedometer can be worn out as a result of regular use, which can affect its accuracy and decline its functionality.

How Can You Diagnose Your Speedometer?

Diagnosing and fixing speedometer issues can be quite simple if you follow an efficient approach.

Here is how you can diagnose the issue with a speedometer.

Check for Obvious Signs

Firstly, you need to see if your speedometer is having issues. Start by observing its behavior. If the needle remains at zero or fluctuates irregularly, it is an obvious sign that your speedometer has some issue.

Check Connections and Wirings

Inspect the connectors and wiring between the speed sensor and speedometer for any visible damage or corrosion. Replace and repair the damaged components.

Scan for Error Codes

Through an OBD-II scanner, you can identify any stored error codes in the vehicle’s computer system. Speed sensor-related codes, including P0501 and p0500, can provide valuable diagnostic information.

Test the Speed Sensor

Depending upon your vehicle’s type you can perform a sensor test. Use a multimeter to check for voltage and resistance on electric sensors.

Examine Speedometer’s Fuse

Locate the speedometer fuse in the vehicle’s fuse box and check if it is blown. The speedometer can stop working if the fuse is blown and you will have to replace it.

How to Fix a Speedometer?

Here are some of the ways to fix your speedometer.

Calibrate the Speedometer

After making modifications to your vehicle’s transmission, gears, and tires, calibrate the speedometer to match the new setting. You might also need to visit a mechanic or dealership with the required tools.

Replace Broken Speed Sensors

If your speed sensor is broken or faulty, replace it with a new one. Choose the correct sensor for your vehicle’s model and make it.

Replace the Speedometer Head

If your speedometer head is defective or damaged physically, the best option is to replace it. This can be mostly seen in old mechanical speedometers.

Repair Connectors and Wiring

During diagnosis, address connector and wiring issues. Repair damaged wires, secure loose connections, and verify correct resistance to resolve this issue.

Consult with a Technician and Mechanic 

If you are not able to identify the issue or fix it, it is preferable to consult with an automotive professional as they have expertise and can easily diagnose and fix the issue.

Update Vehicle Software

If your vehicle has an electronic instrument, by updating the vehicle’s software or by addressing any software glitches, you can resolve the speedometer issues. You can also consult with the manufacturers or dealerships to learn about software updates.

Conclusion

In conclusion, it is crucial for the speedometer to work optimally to ensure a safe drive. If the speedometer is not working optimally, you can face a variety of issues during driving.

There are many possible causes behind these issues, but the good thing is that you can solve many of these causes on your own. However, if you think you cannot manage the work, don’t hesitate to get assistance from a professional mechanic.

So whether you are driving a vehicle with a mechanical speedometer or you are driving a vehicle with an electronic display, it is important to understand and address the issues related to speedometers to ensure safe and worry-free travel.

FAQs

Can I Drive with a Faulty Speedometer?

While it is not illegal to drive a vehicle with a faulty speedometer, it is still unsafe and not a good practice. The functioning speedometer plays a crucial role in maintaining a safe speed and helping you adhere to traffic laws. If the speedometer is faulty, it is essential to get it replaced to ensure your safety and that of others. 

How long can you drive a car with a bad speed sensor?

Even if the speed sensor isn’t working, it will not immobilize your vehicle, and you can still drive it. However, it is not recommended to drive a vehicle with a faulty speedometer.

Why is my speedometer not working?

There are many possible reasons why your speedometer might not be working. These include damaged or faulty speed sensors, compromised instrument clusters, gearbox problems, faults in connections and wirings, sensor calibration issues, and vehicle speed sensor (VSS) failure. 

Why is my speedometer not working, but the odometer is working?

If your odometer is working in good condition, but your speedometer is not functioning properly, it indicates potential issues with the speed sensor or there can be an instrument cluster in your car. What you can do is check the wiring, speed sensor, and instrument clusters for any possible signs of damage. And if need be, get professional assistance.

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