Why is my car running but speedometer not working?

If your car is running but the speedometer is not working, it could be due to a variety of issues, ranging from a faulty sensor to a problem with the speedometer itself. In this article, we'll explore the common causes and provide steps you can take to diagnose and fix the problem.

Common Causes of a Non-Working Speedometer

There are several potential reasons why your car's speedometer may not be functioning properly, even though the vehicle is running. Some of the most common causes include:

• Faulty Speed Sensor: The speed sensor, also known as the vehicle speed sensor (VSS), is responsible for sending a signal to the speedometer, indicating the vehicle's speed. If this sensor is malfunctioning, the speedometer will not receive the correct information and will not display the accurate speed.


• Damaged Speedometer Cable: In older vehicles, the speedometer is connected to the transmission via a mechanical cable. If this cable is damaged, kinked, or disconnected, the speedometer will not receive the necessary input to display the correct speed.


• Electrical Issues: Modern vehicles use an electronic speedometer system, which relies on various electrical components, such as wiring, connectors, and the vehicle's computer (ECU). Any issues with these electrical components can lead to a non-functioning speedometer.


• Speedometer Failure: In some cases, the speedometer itself may be malfunctioning, either due to a mechanical issue or an internal electrical problem. This would require the replacement of the speedometer unit.

It's important to note that a non-working speedometer can also be an indication of a more significant problem with the vehicle's electrical system or drivetrain. Therefore, it's essential to have the issue diagnosed by a qualified mechanic to ensure the problem is properly identified and addressed.

Diagnosing and Fixing a Non-Working Speedometer

To diagnose and fix a non-working speedometer, you can follow these steps:

1. Check for Error Codes: Use an OBD-II scanner to check for any diagnostic trouble codes (DTCs) related to the speedometer or vehicle speed sensor. These codes can provide valuable information about the root cause of the problem.


2. Inspect the Speed Sensor: Visually inspect the speed sensor for any signs of damage, such as cracks, corrosion, or loose connections. If the sensor appears to be faulty, it will need to be replaced.


3. Test the Speedometer Circuit: Use a multimeter to check the voltage and continuity of the speedometer circuit, including the wiring, connectors, and the speedometer itself. This can help identify any electrical issues that may be causing the problem.


4. Replace Faulty Components: If the diagnosis points to a specific faulty component, such as the speed sensor or the speedometer, you'll need to replace the affected part to restore the proper functioning of the speedometer.

In some cases, the issue may be more complex and may require the expertise of a professional mechanic to diagnose and repair. If you're not comfortable performing the diagnostic steps yourself, it's best to have your vehicle inspected by a qualified automotive technician.

Which fuse is responsible for a speedometer?

The fuse for the speedometer is usually labeled something like "Instrument Cluster," "Gauges," or "Speedometer" and is located in one of the vehicle's fuse boxes, commonly under the dashboard on the driver's side or in the engine compartment. The specific fuse number and location vary by vehicle model, so checking your car's owner's manual or the fuse box diagram is essential for pinpointing the correct fuse to inspect.
 
This video demonstrates how to find the fuse for the speedometer in a Chevrolet Silverado: 35sElectrical Car Repair LIVEYouTube · Jun 24, 2023
How to find and check the fuse

1. Locate the fuse box(es): Your vehicle has at least one fuse box, often on the side of the dashboard (visible when the driver's door is open) or under the hood. 
2. Consult the diagram: Find the diagram on the fuse box lid or in your owner's manual. Look for the fuse that controls the "Instrument Cluster," "Gauges," or "Speedometer". 
3. Inspect the fuse: Once you've identified the correct fuse, pull it out and check the metal wire inside. If the wire is broken or looks burnt, the fuse is blown and needs to be replaced. 
4. Replace the fuse: Replace the blown fuse with a new one of the exact same amperage. Using a fuse with a higher amperage can damage the electrical system and is a fire hazard. 
5. Test the speedometer: Turn the ignition on to see if the speedometer is now working correctly. If the new fuse blows immediately, there may be a short circuit or other wiring issue that requires professional diagnosis. 

How much does it cost to fix a speedometer in a car?

The cost to fix a speedometer can range from $50 to $500 or more, depending on the problem, with factors like vehicle make/model, the specific part needed, and labor costs influencing the final price. Minor issues like a speedometer cable replacement may cost $50-$100, while replacing a speed sensor typically costs $100-$200. More complex problems, such as a full instrument cluster replacement, can cost upwards of $500 or even over $2,000 in some cases. 
Cost breakdown by potential fix

• Speedometer cable replacement: Typically costs between $50 and $100. 
• Speed sensor (wheel speed sensor) replacement: Usually falls between $100 and $200, including parts and labor for many common vehicles. 
• Speedometer gear replacement: Generally costs between $50 and $100. 
• Full instrument cluster repair/replacement: This can range from $150 to over $500, depending on the complexity and the specific parts that need to be replaced. 
• Complex repairs: In some instances, such as with certain models or more involved issues, the cost can exceed $2,000 if extensive labor or component removal is required. 

Factors that affect the total cost

• Cause of the malfunction: The specific part that is broken is the primary cost driver.
• Vehicle make and model: The cost of parts and labor can vary significantly between different cars, trucks, and motorcycles. 
• Labor costs: Labor rates differ by location and the type of shop (e.g., dealership vs. independent mechanic). 
• Diagnostics: An initial diagnostic fee may be required to determine the exact cause of the problem before a final repair estimate can be given. 

How to reset vehicle speed sensor?

Reset Speed Sensor

1. Remove the battery.
2. Flip the battery upside down and reinstall.
3. Leave battery installed upside down for 3 seconds.
4. Remove the battery and reinstall correctly. *
5. Make sure the rubber o-ring is back in place and put the battery cover back on.

What would cause the speedometer to stop working?

A non-working speedometer is most commonly caused by a faulty speed sensor or issues with the related wiring, though a blown fuse or a problem with the instrument cluster are also common causes. In older vehicles, a broken or worn speedometer cable can be the culprit, while modern cars might have problems with their main engine control module (ECM) or communication issues between vehicle modules. 
Common causes

• Speed sensor failure: This is one of the most frequent causes. The sensor sends speed data to the car's computer, and if it's damaged or fails, the speedometer won't get accurate information. 
• Wiring issues: Damaged, loose, or corroded wiring or connectors connected to the speed sensor or the instrument cluster can interrupt the signal. 
• Instrument cluster problems: The speedometer is part of the instrument cluster. If there's an electrical fault or a problem with the cluster itself, the gauge can fail. 
• Blown fuse: A blown fuse for the speedometer circuit is a simple but common electrical issue that can stop the gauge from working. 
• Broken speedometer cable: In older cars, a mechanical cable connects the transmission to the speedometer. If this cable breaks, is worn out, or the gears it connects to are damaged, the speedometer will stop working. 
• Engine control module (ECM) or module communication issues: In newer vehicles, the ECM receives the speed signal and sends it to the dashboard. A fault in the ECM or a breakdown in communication between different vehicle modules can also cause a failure. 
• Improper tire size: If you recently changed your tires, incorrect size can lead to inaccurate speed readings. While this doesn't usually cause a complete failure, it will make the speedometer inaccurate unless it's recalibrated. 

What you can do
This video explains what to do if your speedometer is not working: 39sSimple Mechanic AdviceYouTube · Dec 2, 2024

• Check the fuse: The easiest first step is to check the owner's manual to locate the fuse box and inspect the fuse for the speedometer, notes AutoZone.com and TokyoCarZ. 
• Inspect wiring and connectors: Look for any obvious signs of damage, corrosion, or loose connections in the wiring harness related to the speed sensor. 
• Use a scan tool: Have the vehicle's error codes scanned. A mechanic can use a scan tool to check for trouble codes that indicate a faulty sensor or other issues with the electronic systems. 
• Inspect the cable (for older cars): If you have an older car, check the speedometer cable for any damage or kinks, and inspect the gear it connects to on the transmission. 

If these basic checks don't solve the problem, a mechanic will be needed to further diagnose and repair the issue, which may involve replacing the speed sensor, a faulty instrument cluster, or other electronic components.