A speedometer not working can be more than just an annoyance – it’s a safety hazard and can even land you in trouble with the law. But before you panic, know that a non-working speedometer often has a straightforward solution.
This guide will walk you through the most common causes of speedometer failure, from simple wiring issues to faulty sensors, and provide practical steps to get your speedometer back on track.
Contents
Symptoms of Speedometer Not Working
The speedometer determines the vehicle’s speed by drawing information from the transmission and driveshaft.
The ECU (engine control unit) converts the driveshaft’s rotation speed to the vehicle’s linear speed and then passes the information to the speedometer.
When the car speedometer is not working, it cannot translate the information coming from the ECU. A failed speedometer poses a potential safety threat.
The warning signs to look for are:
The speedometer is completely dead! An issue with the speed sensors or speedometer head is the reason. Worn-out connecting cables are the culprits in older cars.
Check engine light comes on. It happens due to a faulty sensor that cannot process the information received from the ECU. It also causes the speedometer to behave erratically.
Frequent changes in the readings. The problem also occurs due to bad wiring or faulty sensors. Re-calibrating the sensors or repairing the wires will solve the issue.
Changing the tires that are larger than the manufacturer’s recommended dimensions can also be the culprit in this case.
The speedometer shows wrong readings because it is calibrated to the dimensions of the factory-fitted tires.
Why Is My Speedometer Not Working?
The speedometers in modern vehicles use speed sensors to calculate the speed while the older models make use of gears and wires for the same purpose. It stops functioning when the sensors don’t work, dials malfunction or the wiring becomes bad.
Look into these components when the speedometer not working.
Malfunctioning Speed Sensor
A speed sensor does not only indicate the vehicle speed but also helps with cruise control operation and regulation of the fuel’s flowing and ignition timing.
A speedometer may stop working due to a bad sensor. Plus, the affected cruise control can disrupt the driving functions of the car. Any problem with the sensor will make the Check Engine light come on.
Issues with the ECU
The Engine Control Unit (ECU) is literally the hub of engine activities, acting as the car’s computer brain.
It monitors and controls multiple engine activities, including speed. It’s obvious that the speedometer may give wrong readings in case of certain ECU problems.
Defective Wiring and/or Fuse
Another reason for the car speedometer not working is a bad wire. The wires can short out for many reasons, causing the fuse to blow out and stopping the operation of the speedometer. It mainly happens in older cars.
Check Error codes
Whether your check engine light is on, your mechanic may begin the diagnostic by utilizing a code reader to see what error codes appear or whether other associated warning lights, such as the ABS light, illuminate.
Checking these codes may provide the mechanic with a clearer understanding of the components that are causing the speedometer to fail.
Your technician may also use a bi-directional scan tool to look for likely reasons in the instrument cluster (gauge cluster).
How To Fix A Speedometer Stopped Working?
Depending on the type, there is only one repair solution for a broken speedometer, replacing either the speed sensor or the wiring.
With proper knowledge about the mechanism of a motor vehicle, you can carry out the repair job at your garage. Otherwise, seeking professional help is the most logical thing to do.
The first step in determining the root of the problem is to use a code scanner to examine the error codes.
Connecting the scanner to the ECU will help pinpoint the failed components. To complete the repair process, the error code must be cleared.
When The Sensors Have Failed
Find the location of the sensors and check them along with the wires connecting to them for any visible damage. Replace the older one with the new unit in case you have found any defects.
When The Wiring Is Bad
The wires can be short or worn out in an older car and cause the fuse to blow out. Examine both the wiring and the fuse and replace the faulty ones.
If The ECU Is The Culprit
Then the entire ECU needs replacement. You can reset it but it will only be a temporary fix. Remember to rotate the ignition key to the ‘Auxiliary’ position after the installation of the new unit.
It will help the ECU to kick off the operation and start adjusting to the other engine systems when the car is turned on.
In every case, don’t forget to test drive the car to make sure that the speedometer is working properly. These are the repair processes that you should resort to in case your speedometer not working.
FAQs About Car Speedometer
How much does it cost to fix speedometer?
The price of fixing speedometer will vary according to the source of the problem. A speed sensor replacement will normally cost between $100 and $200.
A speedometer cable replacement will typically cost between $50 and $100. Moreover, speedometer gear replacement will normally cost between $50 and $100.
Why is my speedometer not working but rpm works?
The fact that your RPM gauge is working while your speedometer isn’t pointed to a few likely culprits:
– Vehicle Speed Sensor (VSS): This sensor is responsible for sending speed data to both the speedometer and the engine control unit (ECU).
– Wiring Issues: There could be a break or loose connection in the wiring harness that specifically connects to the speedometer.
– Speedometer instrument cluster
Can you drive with a speedometer not working?
Yes, technically. However, it is not suggested since you will not know how fast you are going with a damaged speedometer, whether mechanical or electronic.
Not only is this risky, but you can be punished severely for speeding and driving with a broken speedometer.
Can I use my phone as a replacement speedometer?
Because most current phones have GPS capabilities, they can monitor your location and determine your journey speed. There are also speedometer and odometer applications that may help you track the speed and distance traveled by your car.
However, it may not be as precise as your functional speedometer, and you may soon get penalized for exceeding the vehicle speed limit.
In several nations, using a phone as a speedometer is also prohibited. Check your local rules before driving without a speedometer.
Check out this video from Oz Mechanics for more details on how to fix a speedometer that’s not working!
Conclusion
The speedometer is an integral component of the vehicle and is critical to the driver’s and passengers’ safety.
As a result, it is critical to inspect and calibrate occasionally, not until when your speedometer not working, as part of normal maintenance. Due vigilance can help you avoid traffic stuckness caused by a broken speedometer.
my Vehicle dashboard is not working and the car speed is intermittent , on and off. so when i tap on the dashboard it shows data. what could be the issue? my vehicle has KA20 Engine Petrol
My vehicle is a Nissan L/truck 1,500Kg, KA20 Engine, Petrol, 2003 model
It has the problem with the Dashboard going off and the Engine light coming on.
And when being driven it suddenly cuts off speed and picks up again.