Mercruiser 3.0 Speedometer Not Working? Quick Answer

When the pitot tube, which provides water pressure information to operate your boat’s speedometer, becomes clogged, it’s a nuisance. While the Mercury SmartCraft display is capable of extracting speed data from a GPS receiver on boats equipped with it, it has no source of speed information if your boat is not equipped with a GPS unit. You can avoid the fines you could incur for exceeding boat speed limits where imposed, and keep your speedometer working properly with a compressor and a small piece of wire.

When driving a vehicle, it’s important to know how fast you’re going and how far you’ve gone. Therefore, when the speedometer and odometer in your car are not working, they need to be repaired quickly and efficiently. However, unless you’re a mechanic, it can be difficult to determine why these features aren’t working as they should.

Your speedometer and odometer are not working due to a faulty engine control module, a blown fuse or a faulty speed sensor. Analog odometers may not work due to a defective gear or other component.

If your speedometer isn’t working, chances are your odometer isn’t working either, so it’s extremely important to get the problem fixed right away. The rest of this article details the various causes of a not working speedometer and odometer and explains how to troubleshoot these problems. So if you’re having trouble with your car, read on!

Reasons for a faulty speedometer

The speedometer, the component in your car that displays the speed you’re driving, is one of the most important features of a car. In most vehicles, the speedometer is a circular gauge with a gauge that indicates the speed of the car.

On other cars, the speedometer is digitized and the speed is shown as a number that changes with speed.

There are a number of reasons why a speedometer may stop working, which shouldn’t delay repairs. How fast you are driving is one of the most important pieces of information to know when driving so you don’t endanger others and get stopped for speeding.

Let’s discuss some common causes and solutions.

Read: Why is the speedometer not working and the transmission not shifting?

There is a problem with the ECU

The ECU, or engine control unit, is the center of many engine activities, including vehicle speed readings. If there is something wrong with your ECU, you will experience other symptoms alongside your non-working speedometer, including:

The check engine light is on.

Your car won’t start.

An inexplicable drop in fuel efficiency.

You have trouble shifting gears in an automatic transmission.

If you notice these symptoms and your speedometer stays at zero, that’s a pretty good sign that the engine control unit is to blame.

If this is the case, you should take your car to a dealer or repair shop that uses the latest computer diagnostic equipment. For the most accurate diagnosis, take your car to a dealer who sells your vehicle’s make and model.

Unfortunately, ECU repairs and replacements can be expensive, with the part itself costing anywhere from $1,000 to $3,000. If the ECU can be reprogrammed, this repair will likely cost you $300-$700 at a shop.

If you need to replace the part, not only do you have to pay for the part itself, you also have to pay an additional $500-$700 for the labor cost to install and program the new unit.

Read: Automatic Transmission Makes Grinding Noise When Shifting Into Gear. How to repair?

Bad wiring or a blown fuse

If your car has a blown fuse or wire and the speedometer fuse goes bad, the speedometer will drop to zero and stay there. A fuse can blow for a variety of reasons, including poor wiring or wet wires from exposure.

You can take your car to a mechanic to see if this is the problem, or if you are familiar with the car you can check it yourself and replace the fuse if necessary.

Here’s how:

Make sure the car is completely turned off. Consult your owner’s manual to find the location of the fuse box. Most fuse boxes have a card nearby (usually on the lid) that identifies each fuse and circuit. Remove the fuse with a fuse puller. Use a digital multimeter and stick a lead to each pin of the fuse you are checking. If the reading on your multimeter is “OL” the fuse is blown and needs to be replaced. Carefully remove the blown fuse and install a replacement fuse of the correct amperage. Start the ignition to see if you have fixed the problem.

The video below shows you how to change a blown fuse:

Your speed sensor is defective

The speed sensor is one of the most important parts of a car as it regulates ignition timing and fuel flow, displays vehicle speed and controls cruise control. Therefore, a faulty speed sensor reduces your ability to drive your vehicle safely.

Aside from your speedometer not working, here are some other symptoms that indicate your speed sensor is failing:

You have transmission problems, including delayed and harsh shifts.

You cannot activate the cruise control.

The check engine light is on.

You cannot engage your torque converter clutch.

Speed ​​sensors can become damaged over time due to the elements, general wear and tear, and poor vehicle maintenance. To fix this problem you need to replace the speed sensor. You can either take your car to a mechanic and have them do it, or you can do it yourself.

Here’s how:

Park your vehicle, apply the emergency brake and turn off the engine. Place a jack on either side of your car and jack them up so you can slide underneath. Locate the speed sensor, which is located on the right side of the transmission. Disconnect the cable and pull the base of the cable connector out of the plug. Unscrew the screw that secures the sensor and remove it. Align the new speed sensor and screw clockwise into place. Replace the screw to secure the new sensor.

Consult your car’s owner’s manual to ensure you get the correct replacement sensor. Also, make sure you give your car’s parts time to cool before you begin the repair.

Read: Why does the car make noise when turning at low speed?

Why isn’t your odometer working?

If your speedometer and odometer are not working, the problem is likely one of the causes listed above. However, if your speedometer is working and your odometer isn’t, then the problem could be an entirely different one.

When working properly, an odometer gives you an accurate reading of your car’s mileage, which is important for a number of reasons including your insurance, your ability to sell the car, and knowing when your vehicle needs service. Therefore, if your odometer is broken, it is important to have it repaired immediately.

There is one main reason why your odometer could be broken even if your speedometer is fine.

Read: Why doesn’t the car start but the battery is good?

The gears that drive your analog odometer broke

Analog odometers, typically found in older cars, are driven by plastic gears that can break easily.

These odometers have gears and cables that connect the input and output shafts, and when your tires move, the output shaft causes the cable to rotate, causing the gears on the odometer to move.

You will need to remove the instrument cluster and replace the plastic gears to fix this problem. You will need a flathead screwdriver, a T15, a T20 tacks and new gears.

If you don’t have a screwdriver at home, I recommend Amazon’s CRAFTSMAN screwdriver set. The 5-piece slotted set comes with the slotted screwdriver you need to swap out the gears in your odometer, and the blades are heat-treated for extra strength and durability.

Once you have all the materials, follow these steps:

Disconnect the negative pole of the battery. Unscrew the screws at the top of the dashboard. Pull the headlight knob outward so you can see the slot on the side of the plastic. Use your screwdriver to pry into the clip and remove the switch. Remove the instrument cluster. Replace the old, worn gears with your new gears.

This video shows this process in detail:

This is most likely why an odometer won’t work while the speedometer works, so swapping the gears should fix the problem. If it doesn’t, take your car to a mechanic to have them look at it.

Read: Why Does an Automatic Transmission RPM Before Shifting?

Final Thoughts

Speedometers and odometers are essential parts of cars and if yours aren’t working, they should be repaired immediately. Whether you decide to fix it yourself or take it to a mechanic, the most important thing is to get it working again as soon as possible.

This way you keep your status as a safe and responsible driver and car owner!

Knowing the appropriate driving speed is important for all drivers from both a safety and a practical point of view. A non-functioning speedometer increases the risk that you will either be speeding or speeding, potentially increasing the likelihood of an accident or being subpoenaed by a police officer. A working speedometer is essential to safe driving and if you notice that your speedometer is not working properly you should have it checked by a mechanic.

Your vehicle’s speedometer calculates the vehicle’s speed by interacting with the transmission and driveshaft. Your car’s computer is able to translate drive shaft RPM into your vehicle’s linear speed, which is relayed to you, the driver, via the speedometer. A malfunctioning speedometer cannot translate this information and can pose a potential risk to the driver.

ECU Malfunction: The Engine Control Unit (ECU) acts as the computer controlled brain of the vehicle, monitoring many different aspects of vehicle activity, including speed. If there is a problem with the ECU, it can affect the vehicle’s ability to detect the speed it is traveling at and the speedometer will drop to zero.

Bad Fuse/Bad Wiring: In very wet conditions, exposed wires can become wet and short out, blowing a fuse. If the fuse for your speedo no longer works, it can cause the speedo to drop to zero.

Cracked Speed ​​Sensor: A speed sensor has many purposes including showing vehicle speed, regulating fuel flow and ignition timing, and operating cruise control. A failed speed sensor can cause the speedometer to stop working. You may also find that your vehicle is not running smoothly and you cannot use the vehicle’s cruise control. When speed sensors fail, they usually cause the Check Engine light to come on, indicating there is a problem.

A top notch mobile mechanic will come to your home or office to determine why your vehicle’s speedometer has stopped working. The mechanic will then produce a detailed inspection report detailing the reason the speedometer stopped and the cost of any repairs needed.

How it is done:

A mechanic will first examine the vehicle with a code reader/scanner to check for any trouble codes or check engine lights that the vehicle may have generated. By connecting to the vehicle’s ECU, the mechanic can get a better idea of ​​what components may have failed.

If the mechanic thinks the speed sensor has failed, he or she will go under the vehicle to find the exact location of the sensor. Underneath the vehicle, the mechanic examines both the sensor itself and its associated wiring for superficial damage to the unit. The mechanic then removes the old speed sensor and installs the new one.

If the mechanic thinks a fuse or defective wire has caused the speedometer to stop working, he or she will begin examining the fuse to see if it has blown. If so, the mechanic will replace the fuse. The mechanic will also examine the wires that run from the speedometer to the speed sensor to see if they have been damaged in any way.

In the event of a problem with the ECU, the mechanic will usually replace the entire ECU. Since resetting the device may only be a temporary fix, replacing the controller is the only way to ensure it is working properly. When the mechanic installs the new ECU, he or she turns the ignition key to the “auxiliary” position. This allows the new ECU to power up and begin the process of managing vehicle systems. When the vehicle is turned on, it should begin adjusting the systems to run optimally.

For all repairs, a mechanic will clear any trouble codes that may have been generated by the vehicle’s ECU using a code reader/scanner. Before departure, the mechanic will test drive the vehicle to ensure all systems are working properly and the speedometer is functional again.

Speed ​​Sensors: Ultimate Guide (2021)

Would you like to know more about the speed sensor in your car?

The speed sensor is a small device that tells your car’s speedometer how fast you’re going. It plays a role in your car’s transmission and cruise control systems.

In this article, we cover what a speed sensor is and how it works. Then we look at the symptoms of a faulty speed sensor and how often you should replace it.

Finally, we’ll go through the steps required to replace the sensor and highlight the best way to keep your speed sensors in check.

This article contains:

(Click on a link to jump to a specific section)

Let’s get in right away.

What is a speed sensor?

A vehicle speed sensor (VSS) is a small component mounted on your car’s transmission that tells the car’s onboard computer how fast you’re moving.

It is also known as a wheel speed sensor, transmission speed sensor or output shaft speed sensor.

How does the speed sensor work?

The vehicle speed sensor measures the RPM of the gears in your transmission system. It then converts that measurement into an analog signal or a low-voltage square wave signal and forwards it to electronic control units (ECUs) in your car.

The ECUs, in turn, use this signal to adjust your car’s odometer readings, ABS module, and transmission system.

Your car’s cruise control can also rely on the data generated by the speed sensor. Without them, your car would not be able to maintain a constant vehicle speed.

What are the symptoms of a faulty speed sensor?

Since your car’s odometer readings, transmission systems and cruise control all depend on signals from the speed sensor, you need to make sure it’s working as expected.

If you experience any of these symptoms while driving, you may need to check and replace the vehicle speed sensor:

1. Inconsistent speedometer readings

Most cars rely on signals from the wheel speed sensor to adjust their speedometer readings. A faulty sensor can result in inconsistent or erroneous tachometer readings.

Alternatively, there may be no measured values ​​at all.

This does not mean that your car simply stops working and you can no longer drive it.

However, with a broken speedometer, you have no idea how fast your car is going, which can affect your road safety.

If you notice the speedometer acting strangely, you should have your car checked by a mechanic to look for speed sensor failures.

2. The Check Engine Light will be activated

When the Check Engine Light comes on on your car’s dashboard, it can be due to various reasons such as:

A defective ignition coil or spark plug

A defective injector

A defective thermostat

But it can also signal a defective speed sensor.

With a faulty speed sensor, an electronic control unit in your car may not detect a transmission speed sensor signal. And this error can activate your car’s check engine light.

In such a situation, it is best to take your car to a mechanic for an inspection.

3. Cruise control malfunction

In most cars, the cruise control system depends on the input signals from the transmission speed sensor.

So if you have a faulty speed sensor, you probably won’t be able to activate the car’s cruise control.

Why?

In general, the Powertrain Control Module (PCM) in your car will automatically disable cruise control if it doesn’t get a proper signal from the VSS.

This is because without the transmission of speed sensor data, it is impossible to maintain the constant vehicle speed required for cruise control.

If you notice that the cruise control system is not working in your car, have a mechanic come by to check if you have a speed sensor problem.

4. Hard gear shifting

Without a reliable signal from the transmission speed sensor, the powertrain control module cannot properly shift gears in your transmission system.

What does that mean?

The PCM can cause harsh shifts and affect the timing between shifts.

That’s not all.

If your car uses an automatic transmission, a faulty sensor can also cause serious damage to the mechanical gear tooth profile and other internal components like hydraulic lines, valve bodies, and more.

To be safe, you should have an auto inspection done soon to detect any transmission problems your vehicle may have.

How often should you replace the vehicle speed sensor?

There is no hard and fast rule by which you can predict how long your wheel speed sensor will last.

Unlike a brake light switch or caliper, which can last as long as your vehicle, you can expect your transmission speed sensor to last between 30,000 and 50,000 miles.

However, as with brake pads, the lifespan of your speed sensor also depends significantly on your driving conditions. If the speed sensor is frequently exposed to road salt and other compounds, it will not last as long.

In addition, the following conditions can shorten the life of your vehicle speed sensor:

Improper installation of the speed sensor

Electrical faults in the speed sensor wiring

Damaged tone ring

Defective magnetic speed sensor or inductive sensor coil

Contamination of the speed sensor tip

Separation between transmission speed sensor and electronic control unit

Poor vehicle maintenance

To avoid safety risks, consider having your VSS checked as soon as possible if you notice symptoms such as erratic speedometer readings or a non-functioning cruise control, and have it replaced if defective.

How much does it cost to replace a speed sensor?

The cost of replacing the speed sensor depends on the make and model of your vehicle. It also depends on the type of sensor currently used, such as an optical sensor, a magnetic field sensor (Hall Effect sensor) or some other type.

However, replacing the speed sensor is generally not expensive. It costs no more than other major repairs such as replacing brake lines and master cylinders.

That being said, you will likely have to pay between $225 and $380 to replace the vehicle speed sensor.

To get a more accurate estimate, simply fill out this online form.

How to replace your car’s speed sensor

You can try replacing your car’s wheel speed sensor yourself.

However, we strongly recommend getting help from a qualified technician.

Why?

For starters, you will need several tools and safety equipment to safely perform the vehicle speed sensor replacement.

And that includes:

Tongs

multimeter

scan tool

socket wrench

Mechanical gloves

eye protection equipment

And more

Additionally, if you don’t do the replacement properly, you could end up with a defective speedometer or cruise control system, which can affect your road safety and result in higher repair costs.

It’s always better to take your car to an auto repair shop or have a mobile mechanic come by.

When hiring a mechanic, remember to check that they:

ASE certified

Only use quality replacement parts and tools

Offer you a service guarantee

To give you an idea of ​​what speed sensor replacement typically involves, here is a breakdown of what your mechanic will likely do:

1. Place a drain pan or bucket under the sensor to catch any spilled liquid.

2. Carefully disconnect the vehicle speed sensor from the transmission system.

3. Disconnect the connector between the vehicle wiring and the speed sensor.

4. Use a socket wrench to loosen and remove the faulty speed sensor.

5. Install the new speed sensor and reconnect the wiring.

6. Start the car’s engine and take your car for a test drive to make sure the speedometer, cruise control and transmission shifter work as expected.

But where can you find a qualified mechanic who can perform a proper speed sensor inspection and replacement?

The best way to keep your speed sensor in check: RepairSmith

If you’re looking for an easy way to fix your speed sensor, look no further than RepairSmith, a convenient and portable car repair and maintenance solution.

Here’s why you should rely on RepairSmith for all your speed sensor needs:

Speed ​​sensor replacement can be performed in your driveway, eliminating the need to take your vehicle to an auto repair shop

, so you don’t have to take your vehicle to an auto repair shop All speed sensor repair and maintenance work is carried out using high-quality equipment and spare parts

and you can easily book your speed sensor repair online

Repairing your speed sensor You can save money by taking advantage of our upfront and competitive prices.

. Only ASE-certified, experienced mobile technicians service your vehicle

, Expert service for your vehicle All your repairs come with a 12-month warranty with a range of 12,000 miles

Keep your speed sensor up to date

The vehicle speed sensor is a crucial component that ensures your speedometer, cruise control and transmission are working properly.

If you’re driving around with a faulty speed sensor, you may not know how fast you’re going and may endanger your safety and that of those around you. In addition, you are likely to have a poor driving experience due to harsh and erratic gear shifts.

To prevent this from happening, have a mechanic inspect your wheel speed sensor and perform a replacement if necessary.

Luckily, RepairSmith makes hiring mobile technicians easier than ever!

All you have to do is fill out an online form and certified mobile mechanics will come to your driveway to perform the speed sensor inspection and replacement.

So if you are looking for a hassle-free and accessible repair service for your speed sensor needs, contact RepairSmith today!

Disclaimer: As an affiliate, I can earn a commission on all qualifying purchases, including those from Amazon.com, at no additional cost to you – read more.

If you own a motor boat, chances are it has a speedometer. With these nifty devices, you can quickly and accurately measure your ship’s speed so you can navigate better and avoid damaging your boat.

A speedometer is an instrument that shows the speed of your boat. Your boat may be equipped with either a pitot tube, also known as a pitometer, or a GPS gauge. Each measures your speed and provides a gauge for your use. The main differences are accuracy and cost.

That being said, there are so many different types of speedometers that it’s easy to get overwhelmed with all the options available to you when you’re in the market for a new model. Additionally, speedometer care and repair often become an overlooked part of your regular boat maintenance, so we’ve put together this ultimate guide to speedometers, complete with all the information you need to get on the water. Let us begin!

What is a speedometer?

Simply put, a speedometer is an instrument that measures and displays the current speed of a vehicle or ship. Speedometers are presently found in all motor vehicles and are common on most steering wheel operated boats with a console display area.

However, the types of speedometers found on land-based vehicles are actually different from those found on seagoing vessels. For automobiles, your speed on the road is equal to your speed through space. For boats, your speed through water is far more important than your speed through space.

This might sound a bit finicky, but if you’re driving a boat against a strong tide, your actual speed in the water will be different than your speed through space because you’re being pushed back against the tide.

Knowing exactly how fast you’re moving from A to B is essential for timing and calculating whether you have enough fuel to complete your trip.

How does a boat speedometer work?

When purchasing a speedometer for your boat, you actually have a choice between a manual speedometer and a GPS-based speedometer. Both provide estimates of your speed, but they work in very different ways.

A manual speedometer, also called a pitometer, measures your boat’s movement against the speed of the water. It works with a pitot tube that travels along the sea or lake surface and fills with water. The change in barometric pressure from the water gives an instant estimate of your speed, which is fed back to the speedometer on your dashboard.

A GPS-based speedometer shows you how fast your boat is moving through space. It does this by measuring how fast your ship is moving from one position to the next every nanosecond to give you an instant speed readout on your console dashboard. This is the same type of technology found in your navigation device or cell phone.

Is a manual speedometer or a GPS-based speedometer better?

A GPS based speedometer is the best choice for your boat as it is more accurate than a manual speedometer and is not affected by unusual currents or the wind. They’re also much easier to install, but can be affected by particularly inclement weather as they rely on a GPS connection.

If your boat is already set up for a manual speedometer, this is probably your best bet as you’ll already have holes cut into your boat, making the installation process that much easier. However, if you’re starting from scratch, you can mount a GPS-based model on your ship with a little extra legwork.

How accurate is a boat speedometer?

When you buy a speedometer, you want to be sure that you’ve spent your hard-earned money on something that actually works. When it comes to speedometers, there is a wide range of accuracy depending on what model you buy, how you mount it on your boat, and whether it’s a GPS-based device or a pitometer.

For the most part, pitometers are less accurate than GPS models, but as we mentioned earlier, a GPS doesn’t tell you your speed through the water, only in space. Pitometers are finicky, to say the least, and any sort of kinks or problems with the internal pitot tube can introduce accuracy errors.

So if you want a speedometer that always accurately tells you your speed through space, a GPS-based model is the way to go.

Testing the Accuracy of Your Speedometer If you are concerned that your boat’s speedometer is not entirely accurate, you should test it. While there are ways to test the actual pressure in the pitot tube (using a pitometer), these are notoriously inaccurate and complicated. Instead, you can easily test your speedometer’s accuracy by using a GPS-based speed app on your phone while cruising around on a day with minimal wind and calm seas. You may need to account for the tide, but if you can get a sufficiently similar reading between the GPS-based speed app and your pitometer, you’re probably fine.

Choosing a speedometer for a boat

Now that you understand some important information about speedometers, it’s time to discuss how to choose one for your boat. Here are some things to look out for:

1. GPS vs Manual

We’ve already covered this in quite some detail, so we won’t spend too much time on it. Basically, you have to decide whether you want to use a manual or a GPS-based speedometer in your boat.

As we mentioned, GPS models tend to be more accurate, but if you already have holes cut into your boat for a manual speedometer, it might be worth replacing. But modern GPS devices are incredibly accurate, and their sleek, stylish looks might be enough to sway you.

2. costs

In general, GPS-based speedometers cost more than their pitot tube counterparts, so this could influence your decision. However, the accuracy, ease of installation, and simplicity of a GPS device might make the additional upfront cost worth it. Also, GPS units typically require minimal care and maintenance, while pitot tube models require frequent maintenance, which can increase your costs over time.

3.Installation

For the most part, GPS-based speedometers are easier to install than pitot tube speedometers. Because pitot tube models require a pressure tube that sits in the water but connects to the display on your dashboard, more holes need to be drilled, making the installation process more labor intensive. So if you prefer to get the installation done quickly, a GPS-based speedometer might be for you.

Related article: Where should a boat compass be mounted?

What is the best speedometer for boats?

Here are my recommended speedometers for your boat:

Best GPS Speedometer: Eling GPS Speedometer

View on Amazon My top pick is this Eling GPS speedometer with a curved glass display and red backlight. This is very easy to install and shouldn’t take more than 15 minutes. The dial has a white faceplate which is very legible and reads up to 130 km/h (80 mph). I like that it has a very fast startup time of around 3 seconds. It comes with the GPS sensor and cable to attach to the speedometer after installation.

Best Digital Speedometer: Eling Universal Digital Speedometer

View on Amazon For those who prefer a digital dial to traditional style, this universal speedometer is a good choice. This is also GPS based so very similar to Eling’s previous speedometer, however as it is digital there is no limit to the speed that can be displayed. It is IP67 rated and has a range of 7 background colors to choose from. It fits in an 85mm hole and comes with the GPS antenna that can be mounted on top of the dashboard.

Best Manual Speedometer (Pitometer): Sierra International Eclipse

View on Amazon If your boat is already equipped for a pitometer then I recommend Sierra International’s Eclipse kit. It includes a 3-inch white and blue dial with wraparound backlighting for easy viewing at night. The kit also comes with a pitot and hose so you only need to purchase one product.

How to install a speedometer on a boat

Properly installing a speedometer on your boat is critical to ensuring it is accurate and effective over the long term. If the speedometer is not installed properly, you can end up getting very inaccurate speed readings that can endanger you and your boat.

When it comes to installing a speedometer, you have two options: do it yourself or hire a professional. This is what these two options would look like:

Option 1: do it yourself

Installing a speedometer on your boat doesn’t have to be an impossible task. In fact, depending on the type of speedometer, the process can be quite simple. Here’s what you need to do:

How to install gps speedometer

There are three main steps to installing a GPS speedometer:

Decide where you want to mount the GPS display on your dashboard. Once you find the right spot, follow the device’s instructions to drill a hole in the fairing and insert the speedometer. Attach the speedometer and its bracket to the back of the fairing as instructed in the owner’s manual. Connect the device to a 12 volt power source. The vast majority of GPS speedometers require some form of ground connection and two 12 volt power connections. One of these connectors is used for the backlight, the other is essential for the operation of the actual device. Usually the other instruments on your boat are already hooked up to good power sources that your speedometer can share.

Check prices on Amazon

How to Install Pitot Tube Speedometer

Installing the pitot tube speedometer is a bit more complicated than installing GPS models, but not impossible. To start, I recommend getting this SeaChoice pitot speedometer kit, which includes everything you need to install a pitot on the outside surface of your boat. The kit includes a flexible pitot that can pivot, black plastic vent, black plastic pipe holders, self-tapping screws, and 20 feet of PVC tubing. View on Amazon

Here is a step-by-step guide to installing a pitot tube speedometer:

Drill a hole in your instrument panel to mount the speedometer gauge. Follow the device’s instruction manual to ensure you drill the correct size hole and attach the mounting bracket properly. Determine which route your pressure hose will take in your boat. The speedometer display is connected to the pitot by a stiff tube that can transmit water pressure from the pitot to the display’s sensor. The tube itself must always slope downwards, as sagging in the tube can cause water to collect inside and affect the accuracy of the instrument. Decide where on the transom you will mount the head tube. The pitot tube should sit in a location where there are no potential sources of damage such as rudders, propellers, trim tabs and guard rails. The tip of the pitot tube should be at least two inches below the hull. Once you find a good spot to mount the pitot tube, you can screw the pitot mount into the transom and make sure the pitot is pointing straight down. Drill a hole in the transom for the pressure pipe. The hole should be well above the waterline and sloped down about 45 degrees. Insert the pressure tube into the hole and connect it to the pitot. Secure the pressure pipe with cable clamps and sealant. The other end of the pressure hose should be connected to the speedometer gauge.

Option 2: Professional Installation

If do-it-yourself projects just aren’t your thing, you can always pay a professional to install your speedometer for you. As we mentioned, this is not an overly complex process, so it should take a skilled ship mechanic quite a bit of time at all.

Generally, a professional should be able to complete the project in under an hour if you provide all the parts. So depending on the prices at your local marine shop, it won’t cost you too much money to pay someone to install your speedometer.

Repair and maintenance of your speedometer

Like all good marine equipment, speedometers require frequent repair and maintenance to remain in good working order. When it comes to GPS speedometers, as long as they have a good electrical connection and the software stays up to date, you really don’t need to do all that much repair work.

If you are having trouble with your pitot tube speedometer, the likely cause of the problem is the tube itself. To identify and troubleshoot the problem, you should take a look at the tube and inspect it for holes and cuts. If there is no obvious damage, you should make sure water isn’t collecting in the tube, causing it to sag and give an inaccurate reading.

If this doesn’t solve your problems, you may need to replace the tube. Thankfully, the tube isn’t all that expensive, so you should be able to get some from your local marine store without breaking the bank. Just make sure you buy the same length of tubing as before to avoid any potential problems.

Generally, installing a new tube will solve most problems, but if not, it might be time to call in a professional. These devices are notoriously tricky, so it’s worth getting help with repairs if you’re not entirely sure what the problem is.

Inside a Mechanical Speedometer A flexible drive cable in a flexible tube connects a small magnet inside the speedometer to the transmission output shaft. The magnet rotates with the shaft and its magnetic field attracts a metal drum to turn the speedometer needle against the force of a hair spring. The needle moves around the dial until the restraining force of the hair spring brings it to a halt to read the driving speed.

Of all the instruments you can find on a modern car dashboard, only one is required by law – the speedometer and its built-in odometer (also called an odometer). As with other developments in automotive technology, the trend is now towards the use of electronics in speedometers. But most cars – including those built today – have a mechanical speedometer, usually with a needle and a calibrated dial to show speed. The design of this type of speedometer has changed little in the last 50 years.

operation

Mechanical speedometers measure a car’s speed by being mechanically connected to the transmission output shaft. Because this shaft is “downstream” of the transmission, the speed at which it rotates is independent of gear changes, giving a true measure of road speed.

transmission output shaft.

Inside the gearbox, the output shaft contains a gear that rotates with the shaft. Connected to and driven by this gear is a small pinion, the speedo chive pinion, which in turn is connected to the speedo cable leading to the speedo itself. The speedometer cable consists of an inner cable that runs in a protective outer sheath. The ends of the inner speedometer cable are angular and fit into the square holes in the drive pinion on the gearbox and in the drive at the back of the speedometer. As the pinion rotates, driven by the transmission output shaft, it causes the inner cable to rotate with it. The other end of the cable fits onto a driveshaft that goes into the speedometer. At the end of this shaft is a magnet. Near the magnet (without touching it) is a cup-shaped metal drum attached to the needle that displays the reading on the dial. A small spiral spring keeps the needle at zero.

Needle The magnet causes a needle to move around a circular disc.

The drum is attracted to the magnet, so when the magnet rotates, the drum rotates with it. The faster the car drives, the greater the pull of the magnet on the metal drum, and the further the needle moves around the dial. But the hairspring’s restraining force also increases as the needle moves around the dial. At a certain point, the forces of the spring and magnet balance and the needle stabilizes to give a reading.

variations

The other two common types of mechanical tachometers give the reading by a bar or marker moving along a straight calibrated scale. Both are roughly similar in operation to round-dial tachometers – a cable, driven by the gearbox output shaft, turns a magnet that causes some sort of indicator to move against the force of a restraining hairspring.

Ribbon The magnet causes a ribbon to be rolled from one spool to the other. A mark on the tape measures speed using a straight scale.

In one type, the indicator consists of a moving tape attached to a spool at each end. The magnet causes the ribbon to unwind from one spool to the other against the force of the hairspring. As the ribbon moves, a mark on it aligns with the calibrated scale to show a reading.

Drum The magnet rotates a drum. A mark on the drum aligns with a straight scale to indicate road speed.

The other type of indicator, which uses a straight scale instead of a dial, has a barrel marked with a line. The magnet causes the barrel to rotate until stopped by the hair spring. As the barrel moves, the mark on it again aligns with the scale to indicate velocity. In both types of speedometers, the tape or barrel on each side of the marking line is usually a different color to make it easier for the driver to read the speed.

How an Odometer Works How an Odometer Works Because the speedometer measures the rotation of the transmission output shaft, it’s relatively easy to use this information to determine how far the car has traveled. This is why the odometer (often referred to as the odometer) is built into the speedometer. The odometer is operated by a small gear connected to the inner cable where it joins the speedometer. This gear drives a series of gears that turn separate drums that bear the numbers 0 through 9. The gearing is arranged in such a way that each number clicks into place after the correct distance and, when it reaches the number 9, advances its neighbor by 1. Some cars have two kilometers m. One (called a trip meter) the driver can reset via a dashboard-mounted control to measure distances. The other odometer cannot be reset to ensure that it measures the mileage the car has traveled over its lifetime, or at least until it “runs 24/7” (typically 100,000 miles). All cars have the second type of odometer; only some also have the first.

Electronic speedometers

Along with the trend towards electronic dashboards, electronic speedometers are becoming more popular, although mechanical ones tend to be reliable. The most common type has a magnet attached to the transmission output shaft and an electronic unit positioned nearby to act as a pulse generator. Each time the rotating magnet passes the pick-up unit, the unit sends an electrical current pulse down a wire to the speedometer. An electronic “black box” in the speedometer uses these pulses to calculate the car’s speed.

Marine gauges are a window into the operation of your boat, letting you know what’s happening in your systems and alerting you to impending danger. However, they can only do this if they are in perfect condition. Because marine conditions tend to be inhospitable to electronics, marine gauges often require more maintenance than their inland counterparts. Although repairing them may seem complicated, it’s just a matter of the basics, how they work and what to do. As with many boat trips, the most important step is to pay attention. Keep a close eye on your gauges so you can spot their problems before they affect the safety of your boating experience.

As a note, this is a general guide. You may want to check your manual for information specific to your meter type. On a boat, some of the most common types of gauges on the dashboard are tachometer, fuel, speedometer, trim, voltmeter, oil pressure, and water temperature gauges. Trim, a gauge found only on boats, measures how much the engine is raised or lowered.

Components for marine gauges

Fortunately, ship gauges are not complicated in their construction. With a faulty meter, three components can be the source of the problem: the meter itself, the wiring, or the transmitter.

Most gauges have at least three connectors on the back. The “S” or “SND” terminal is connected to the transmitter, which is the device that measures fuel level or water temperature or oil pressure and sends that measurement to the front of the gauge. The “I” or “IGN” terminal is connected to the ignition and sends power to the gauges. The “G” or “GND” terminal is the ground connection for the lighting circuit. These are the three basic terminals; Some gauges can have up to five. If your meter has more than these three, consult the manual for the device and make sure you know what they are for exactly.

Troubleshooting and repair of ship gauges

Although it is important to properly check all the components of the gauge, in many cases it is the transmitter that is causing the problem, especially when it comes to the fuel gauge. Fuel gauges are often notoriously inaccurate because they use a float system to determine fuel level, which is problematic because bumping over the waves or the simple fact that the tank may not always be level will alter the readings displayed by the transmitter.

The two main problems gauges usually have are that they either don’t work or read incorrectly. Incorrect readings can be more dangerous because at first glance the meter appears to be working.

If the display does not work, disconnect the transmitter connector and turn on the ignition. With the ignition on, the gauge pointer should be at the far left. If this is not the case, you will need to check the ignition voltage by connecting a multimeter between the ignition and ground terminals. If there is no voltage, check the wiring going to the ignition and ground as that is most likely the problem area. If the pointer is all the way to the left, short the transmitter connector to ground. If the pointer does not move all the way to the right, the gauge is defective and must be replaced. If the pointer moves all the way to the right, the problem is either with the wiring to the transmitter or with the transmitter unit itself. Check the wiring and retest; If the problem is not resolved, you will need to replace the connector.

If the meter is reading incorrectly, your first step should be simply to check the clamps and see if they are loose or dirty. If it is, clean and tighten, and if that is not the cause of the problem, continue with the rest of the process. Check that the meter is calibrated using the test ohms as specified in the manual. If the meter does not calibrate, the meter is defective and must be replaced. If the meter calibrates, the problem is with the transmitter and the transmitter needs to be replaced.

If you need to replace a transmitter unit, remember that a transmitter must be grounded and therefore have metal-to-metal contact with its threads in order to function. Be careful with thread sealant or the transmitter will not work. When replacing a tank sender, be sure to measure the tank as senders come in a variety of lengths and you will need to select the one that meets your specific needs.

Standard sea cable code

If you need to replace wire, be sure to use the correct wire colors as required by the Standard Marine Wire Code. The colors are used as follows:

Red – Constantly hot

Black – mass

Purple – Key-on Power (between the meter and the key switch)

Yellow/Red – Neutral security

Light brown – water temperature

Dark Blue – instrument lights

Pink – tank transmitter

Gray – Tachometer Light

Blue – oil pressure

Brown/White – Trim Indicator

Brown – bilge pump

Green/White – Trim down

Blue/White – Trim up

Green/Orange – Independent tilt down

Blue/Orange – Independent tilt up

Yellow/Black – Throttle circuit

Yellow/Red – Start circle

Black/Yellow – Ignition

When troubleshooting and repairing gauges, remember to take extreme precautions since you are working with both combustible materials and materials that can give off electrical shock. Keep an eye on yourself and the tanks and gauges. When purchasing replacement devices, you should have the specifications of your existing devices with you so you can be sure that your new purchases will be compatible with them.

The more you know about how to fix something on board your boat, the more comfortable you’ll feel on it and the happier you’ll be when you’re on the water. Learn to understand and repair your gauges, and you’ll be well on your way to becoming a skilled boater!

Voltmeter connection circuit.

Gauges and gauges sit unobtrusively on our marine engine control panels, switch panels and navigation stations; They are windows into our boat systems and without them, systems and equipment would function invisibly and fail without warning. Such devices are critical to ensure that boat engines run correctly within normal operating parameters and electrical systems are not overloaded.

Circuit of the water temperature meter.

Today our gauges and gauges can be a range of discrete analog gauges, just a few simple gauges, or a new generation of integrated digital and visual screen displays. I’m still one who prefers analog displays, and there’s a good reason planes still use them as parts of the latest high-tech screens. A quick glance is enough to see that your systems are “go”. This is an important point to remember, because when it comes to meters and gauges, it’s not always about numbers; It is also about monitoring uptrends or downtrends of the system the meter is monitoring.