The speedometer is an essential part of your instrument cluster on your dashboard. Not only does it tell you how fast you’re going, the speedometer is often connected to the odometer, which tells you how many miles or kilometers your vehicle has driven.
If your speedometer is broken, you will need to first determine which type of speedometer you have in your vehicle. Some models use both types of speedometer implementations (even within the same generation), and the one you need will depend on the year your vehicle was manufactured.
How Does a Speedometer Work?
There are two types of speedometers: cable-driven speedometers and electronic speedometers.
Cable speedometers use a cable attached to the transmission. This cable runs from the transmission, through the firewall and into the cabin. It it plugged into the back of the instrument cluster, translating the spinning movement from the transmission into a speed readout on the dash.
Instead of a cable, electronic speedometers use a speed sensor. This sensor feeds transmission speed data to the ECU, which then translates this data into a ground speed reading for the instrument cluster.
Reasons Your Speedometer Isn’t Working
1) Worn Speedometer Cable
If your speedometer needle is jumping or working intermittently, you may have a bad speedometer cable. As the cable wears out, it may bind or work intermittently. These are signs that the cable needs to be replaced.
2) Bad Speed Sensor
A bad speed sensor affects electronic speedometers. If your speed sensor goes out, has a grounding issue, or the wiring is bad, the ECU has no way of knowing how fast the transmission is spinning, and therefore can’t tell you your speed.
3) Bad Instrument Cluster
The speedometer often stops working if your instrument cluster starts to fail. If you have a bad cluster, you may also notice other gauges appear to quit working, such as the coolant temperature gauge and the fuel gauge.
If multiple gauges seem to act up at the same time, you more than likely are having an issue with the instrument cluster, not the speedometer cable or speed sensor.
How to Fix a Broken Speedometer
The proper fix for a broken speedometer will depend on the type of speedometer you have and the root cause of the problem.
For Cable Speedometers
When you have a cable speedometer, the fix is often as simple as replacing the broken speedometer cable. This cable may be hard to reach for some people on some vehicles, as it usually runs underneath the vehicle close to the transmission.
For Electronic Speedometers
If you have an electronic speedometer, you should notice a check engine light if your speed sensor has failed. Perhaps the speedometer works intermittently, or you get a code for the speed sensor, such as P0501.
Inspect the wiring leading up to the speed sensor and any grounds used by that sensor. If the wiring looks good, replacing the speed sensor should resolve the problem.
Can You Drive Without a Speedometer?
While you can drive perfectly fine without a speedometer, it may not be legal for a few reasons. If your state or country requires a working speedometer for the vehicle to be road legal, you may face fines if you drive with a broken speedometer.
The speedometer and odometer are often connected. If the speedometer fails, chances are the odometer will stop working as well. This means that in some cases, you cannot accurately track the mileage on a vehicle that has been driven without a working speedometer.
If the odometer stops working along with the speedometer, make sure you disclose that the odometer reading is not accurate if you go to sell the vehicle. You could get in a lot of trouble if you attempt to sell a vehicle and knowingly underrepresent that vehicle’s mileage.
Will Your Phone Work as a Speedometer?
Your phone’s GPS is quite accurate, and can even be more accurate than the speedometer your vehicle came with. This is particularly true if you’ve changed the tire size of your vehicle, and the speedometer was not recalibrated to account for this change.
While it is possible to use certain apps on a smartphone as a substitute for a speedometer, it is not always legal to do this. Check the laws in your area before using your phone instead. If you need to use your phone, make sure it is mounted in a hands-free location so you don’t risk an accident.
Speedometer Repair Cost
The cost to repair or replace a speedometer will depend on the root cause of the problem. A broken speedometer cable will cost you around $20-100 to do it yourself, but could cost closer to $300 if you take the vehicle to a shop.
A speed sensor costs around $20-50 to replace if you do it yourself, but could cost closer to $200-300 if you take it to your mechanic.
Instrument clusters are often fairly straightforward to replace, but the cluster itself is pretty expensive. Expect to pay between $500-800 for the cluster, depending on the vehicle.
You may be able to find substantially cheaper prices if you visit an auto salvage yard. You could also opt to have your current cluster rebuilt.
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