What to check if speedometer is not working?
The speedometer is a crucial component of your vehicle, providing real-time information about your speed to ensure safe driving. When it stops working, it can be both frustrating and dangerous. At Kevin's Autos, with years of experience in car maintenance and repair, we’ve seen this issue many times. Here’s a detailed guide on what to check if your speedometer isn’t functioning properly.
1. Inspect the Speed Sensor
The speed sensor is one of the most common culprits when a speedometer stops working. This sensor is typically located on the transmission and measures the rotational speed of the transmission, sending this data to the speedometer.
- Check for any visible damage to the speed sensor.
- Ensure the wiring connected to the sensor is intact and not corroded or frayed.
- If the sensor is faulty, it may need to be replaced.
Replacing a damaged speed sensor is often a straightforward fix that restores the speedometer's functionality.
2. Examine the Speedometer Cable
In older vehicles, a mechanical speedometer cable connects the transmission to the speedometer. Over time, this cable can wear out or break.
- Inspect the cable for any signs of wear, kinks, or breaks.
- If the cable is damaged, it will need to be replaced.
- Ensure the connections at both ends of the cable are secure.
For vehicles with mechanical speedometers, a faulty cable is a common issue that can be resolved with a replacement.
3. Check the Instrument Cluster
The instrument cluster houses the speedometer and other gauges. If the speedometer isn’t working, the issue could lie within the cluster itself.
- Look for any blown fuses related to the instrument cluster.
- Check for loose or damaged wiring behind the cluster.
- In some cases, the speedometer gauge may need to be repaired or replaced.
Problems with the instrument cluster may require professional diagnostics to pinpoint the exact issue.
4. Test the Vehicle’s ECU
The Engine Control Unit (ECU) processes data from the speed sensor and sends it to the speedometer. If the ECU is malfunctioning, it can disrupt the speedometer’s operation.
- Use a diagnostic tool to check for error codes related to the speed sensor or ECU.
- Ensure the ECU is receiving and transmitting data correctly.
- If the ECU is faulty, it may need to be repaired or reprogrammed.
Issues with the ECU are less common but can be more complex to resolve, often requiring specialized equipment.
5. Inspect the Wiring and Connections
Faulty wiring or loose connections can interrupt the flow of data from the speed sensor to the speedometer.
- Check all wiring related to the speed sensor and instrument cluster for damage or corrosion.
- Ensure all connections are secure and free of debris.
- Repair or replace any damaged wiring as needed.
Electrical issues can sometimes be tricky to diagnose, but thorough inspection often reveals the problem.
Conclusion
A non-working speedometer can stem from various issues, ranging from a faulty speed sensor to problems with the instrument cluster or ECU. By systematically checking these components, you can identify and resolve the problem. If you’re unsure or need professional assistance, don’t hesitate to bring your vehicle to Kevin’s Autos. Our experienced technicians are here to help you get back on the road safely and confidently.
Frequently Asked Questions
Can a bad alternator cause the speedometer not to work?
If you notice your windows taking longer than usual to roll up or down, or if your seat warmers feel “off,” or even if your speedometer and other instruments start going haywire while the vehicle is running, you may have an alternator problem.
How do you get your speedometer checked?
To test you can do one of two things. Easiest: Get a GPS speedometer app on your smart phone. Plug in a device into the OBD-II port on your car. And look up the speed value. This value is what the ECM is getting from the Vehicle Speed Sensor. It is accurate.
What can throw off your speedometer?
UPSIZING OR DOWNSIZING
Up-sizing, or installing a taller tire, will lead to a speedometer reading that displays slower than your actual speed. This is because a taller tire will have a larger overall circumference, causing it to need to travel more distance per revolution than the original equipment tire.
What electrical issue can make my speedometer stopped working?
Start by inspecting the fuses related to your instrument cluster and speedometer. A blown fuse can often be the culprit. Inspect wiring and connectors. Examine the wiring and connectors associated with the speed sensor, speedometer cable, or VSS for any visible damage.
How to test a speedometer?
A vehicle's speed and accuracy of the speedometer can be made by measuring the time it takes to travel one mile. The best way to conduct the test is to set cruise at one speed and measure the time it takes to travel between two green mile markers on Interstate or other US/state highway.
What sensor controls the speedometer?
The vehicle speed sensor (VSS) or output transmission speed sensor determines how fast your vehicle is going by measuring the rotation of a toothed wheel on a shaft inside the transmission or at one of the wheels if the signal is coming from the ABS module to the PCM or TCM.
What to do if the speedometer is not working?
Pop the hood and open the fuse box. Locate the fuse for the speedometer and remove it. Hold the fuse up to a light to see if the wire inside is broken. If it is, replace the fuse.
What are the signs of a bad alternator?
How Do You Know if a Car Alternator is Bad?
- Trouble starting your car.
- Frequent stalling.
- Whining or screeching noise after the vehicle starts.
- Dim or overly bright lights.
- Smell of burning rubber or wires.
- Dead battery.
- Battery dashboard warning light is on.
How to check if a speedometer is bad?
Top 3 Signs of a Broken Speedometer
- 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.
- Speedometer Needle Jumps and Skips.
- Squealing Noises.
Can I still drive my car if the speedometer doesn't work?
Driving with a broken speedometer makes it difficult to abide by the legal speed limit. More than hefty fines, you can seriously put lives in danger by continuing to drive your vehicle without getting this gauge repaired.
