What if my speedometer isn’t working?
We don’t think much about our speedometers until they stop working and we have no idea what our speed is. While it seems like a pain to fix it yourself, some problems are easy to fix. In this article, we’ll explain how a speedometer works, common causes of failure, and how much it costs to repair.
How a Speedometer Works
Simply put, a speedometer is a device that measures the speed of a vehicle with high accuracy. For decades, vehicles of all types have come standard with a speedometer built into the dash.
Cable-Driven Speedometers
The majority of early speedometers were cable-driven. Most of these systems used a flexible cable attached to a gear that was driven by the transmission’s output shaft. On the other end of the speedometer cable was a magnet that rotated inside a speed cup.
The resulting magnetic field would cause the speed cup itself to start moving. The rotation of this speedometer causes an attached measuring needle to move, allowing the driver to accurately gauge the vehicle’s speed.
Electronic Speedometer
Today’s modern vehicles rely on the use of electronic speedometers. These speedometers use a speed sensor that detects pulses from the gear teeth attached to the output side of the vehicle’s transmission.
These pulses are interpreted by the vehicle’s control module, which sends a corresponding signal to the vehicle’s instrument cluster.
The pulse frequency detected by the vehicle’s speed sensor increases during acceleration, thereby changing the signal sent to the corresponding module. Similarly, deceleration produces an opposite response to the speed sensor’s pulse frequency.
Why Your Speedometer Won’t Work
There are a number of reasons why your car’s speedometer may fail. However, some failures are much more likely than others. Below are some of the most common causes of speedometer problems:
1. Damaged or faulty speed sensor
2. Damaged speed sensor wiring
3. Damaged instrument cluster
4. Faulty ECU
How to fix a broken speedometer
Before repairing your speedometer, you must first identify the root cause of the problem with your vehicle. The operation of the speed sensor and the integrity of the circuit can be checked using a multimeter or quality diagnostic tool. Similarly, the vehicle’s instrument cluster can be checked using a two-way diagnostic tool.
A simple visual inspection can also help diagnose speedometer problems. The vehicle’s speed sensor and associated wiring and connectors should be inspected for signs of damage or wear. You can also observe the function of the instrument panel to look for abnormalities.
Often, you may notice the speedometer needle skipping or have intermittent errors. If your vehicle’s speed sensor is found to be defective, it will need to be replaced. Simply remove the holder for the problematic sensor, pull the sensor out of the hole, and replace the problematic sensor.
Repairing wiring errors is a bit more difficult and requires identifying the damaged part of the affected circuit. In these cases, you can purchase a replacement wire harness or harnesses. Alternatively, in some cases, you may be able to repair the circuit.
If your car’s speedometer is found to be defective, the instrument cluster will need to be removed. This often involves removing select dashboard components and associated hardware. You can then choose to purchase a new/reconditioned instrument cluster or have the damaged instrument cluster repaired.
If an ECU failure is suspected, further diagnostics should be performed in accordance with factory-specific service materials. While this type of computer does indeed fail from time to time, this type of problem is relatively rare.
Can I drive a car if my speedometer stops working? Technically, it is possible to drive a vehicle with a non-functioning speedometer. However, this is not recommended.
Without an alternative solution, you will not be able to detect the speed of your vehicle. Not only is this dangerous, but it also significantly increases the risk of being prosecuted by the police for a traffic violation. Simply put, there is little chance you can avoid a speeding ticket just because your speedometer isn’t working. In any case, a faulty speedometer should be repaired as soon as possible.
Can I use my phone as a speedometer instead?
All modern smartphones have GPS built in. So your phone can accurately record your location and how fast you’re driving. Many curious people have taken advantage of this knowledge and developed speed monitoring apps.
If your speedometer breaks down, you can use a speed monitoring app, such as the popular Speedometer Speed ​​Box (for iPhone) or GPS Speedometer (for Android) apps, to monitor your vehicle’s speed. There are many other similar apps (free and paid) that serve the same purpose.
However, drivers should be aware that apps of this type are not always completely accurate.
