How to Tell If a Fuse Is Blown in Your RV, Van, or Boat

How to Tell If a Fuse Is Blown in Your RV, Van, or Boat

R
Renogy
Oct 15th 2024

While a small yet significant piece in a somewhat large jigsaw, a fuse is what keeps everything electrical operational. We hardly notice it when everything is going right. But when the lights or radio unexpectedly go off in your RV, van, or boat; you instantly think of the fuse. But is there a workaround on how to tell if a fuse is blown?

I mean it could easily be something else that has cut the power to your vehicle. In this article, we shall define what a fuse is, how it works, and most importantly how to tell if it has blown. So, let’s dive in.

What Is A Fuse?

A fuse is essentially an electrical device that acts as a fail-safe to prevent overcurrent burning the power circuit. In vehicles, a fuse features a thin wire strip also known as a filament that connects two terminal blades. It is visible through the colored plastic if you look keenly. Fuses are very crucial in maintaining electrical safety.

Their simple but effective action to cut power when there’s a current overflow protects the other electrical components and also prevents fires. Most vehicles such as RVs, boats, cars, and trucks have fuses to protect their electrical components in case of a surge in current flow.

Where Are Fuses Located?

Most vehicles have at least two fuse boxes, each with a different purpose. There is one located near the battery of the vehicle under the hood (bonnet). The second one is located somewhere within the vehicle. The one under the hood is meant to protect the engine and other components like the cooling system and the engine control unit.

The interior fuse box protects interior electronics such as lights and radio, among others. In five-wheel RVs and trailers, there’s typically one fuse box for the interior. However, motorhomes are known to have 4 or more fuse boxes. To be sure of how many your vehicle has, check the manufacturer’s manual.

By doing so, you’ll also be able to locate the fuse box when you have a blown fuse. Looking for a blown fuse can be a nightmare especially if you are uncertain on where to look. Some RV manufacturers place fuses in hidden spots such as doors. So, make sure to meticulously read your manual to easily locate them.

The first sign that you have a blown fuse is when a certain electronic isn’t functional. If suddenly a socket or radio isn’t working then most likely there is a broken fuse that requires some attention. If the fuse is under the hood, you will get a warning light on the dashboard and the vehicle won’t start.

What Does A Blown Fuse Look Like?

What does a blown fuse looks like

After you have ascertained that some function isn’t working, you now have to look for the blown fuse and replace it. But what does a blown fuse look like? That’s pretty simple. After you have successfully located the fuse box, look out for one with soot (blackening) around it.

Sometimes even the cover plastic of the fuse is melted, so you can easily spot it. If all the fuses in the fuse box look intact, then go for a closer inspection of each. Fuses are usually made of colored translucent plastic. So, look out for one with a broken filament inside, that’s your blown fuse. This approach works fine for simple vans.

But when dealing with motorhomes and RVs that potentially have 30 or more fuses, it can easily turn into a nightmare. To ease your search, you’ll need a manufacturer’s manual. The manual will direct you on which fuse connects the electronic that has stopped working and this way you can swiftly replace it.

In some advanced vehicles, the fuse box has different lights just next to the fuses. These either illuminate or go out in case there is a blown fuse. If you still can’t locate the blown fuse then contact your mechanic, it could be something else altogether.

Why Do Fuses Blow?

Every electrical component manufactured today typically has a fuse inserted in it as a fail-safe in case there is an overflow of current. When there is a surge in current following through the circuit, it blows and cuts power to the rest of the system.

This is meant to prevent substantial damage caused by overheating. Fuses also curb electrical fires that could result from too much current reaching other electrical parts of the vehicle.

5 Signs You Have A Blown Fuse

Signs you have a blown fuse

There are several ways to tell when you have a blown fuse. Here are 5 telling signs that you might have a blown fuse.

The electronic unexpectedly stops functioning

The first indicator that you might have a blown fuse is when an electronic unexpectedly stops working. Let’s say you are listening to the radio and it goes off and won’t switch back on. That’s a sign that a fuse that caters to the radio has blown and needs your attention.

Faint burnt plastic smell

Sometimes you’ll get a faint smell of burning plastic as soon as the fuse blows. This is common with interior fuses. If you get that smell then locate and replace the broken fuse.

Dashboard Warning Light

When the affected fuse is blown under the hood, you might get a warning light on your dashboard indicating there’s an electrical problem. But this varies with different vehicles. In less advanced ones, the dashboard lights won’t come on and the vehicle won’t even start.

Dimming and Flickering Lights

Sometimes just before a fuse blows, you see flickering or dimming of lights. When this happens, that’s a sign that the circuit is overloaded and could cause a fuse to blow up. It could also mean you have a bad or weak fuse that needs to be replaced.

No Response from Accessories

If you ever reach for a car charger or cigarette lighter and it doesn’t work, that right there is a sign that you might have blown a fuse.

How to Fix A Blown Fuse

How to fix the blown fuse

After you have experienced any or the all signs we mentioned above, it’s time to find and replace the blown fuse. While there’s always a temptation to call a mechanic to have a quick look, remember they tend to exaggerate the diagnosis to trick you into paying more than you are supposed to. Fixing a blown fuse isn’t rocket science and can be done by anyone. Let’s guide you through the process and you’ll see just how easy it is.

1.Turn off the Vehicle

Before doing anything, turn off the engine. This way you can avoid any further electrical mishaps.

2.Locate the Fuse Box

If you have identified what electronic has stopped working then it’s much easier to locate the fuse box. If you got a warning light on your dashboard or if the car suddenly won’t start then the obvious fuse box to check is one under the bonnet. If it’s something like a radio or cigarette lighter, then look for the interior one. It’s usually located in the passenger or driver foot area. However, confirm first with the manual before stripping the car.

3.Identify the Fuse

After you have located the fuse box in question, you must now find the blown fuse. Sometimes it’s rather obvious and you will see it right away. If you see a blackened fuse or one burnt out then that’s the one you need to replace. If everything looks okay on the face value then turn to your manual and see which fuse attends to the faulty electronic.

4.Remove and Inspect the Fuse

If you had to look at the manual to find the fuse then the next step is to remove and inspect it. Most vehicles have a small fuser fitted in the fuse box. If yours doesn’t have one, use a pair of needle nose pliers to remove the fuse. To inspect the fuse, look closely through the translucent plastic for a broken filament.

Sometimes it might be hard to tell if there’s a break in the filament. If you are certain that you have located the right fuse then test it out with a multimeter. A multimeter is a tool designed to measure electric current, voltage, and resistance, over varying ranges in value. To test the fuse using the multimeter, set it to the continuity setting. Then place the multimeter probes on each terminal blade.

In a continuity test, the multimeter will send a small current through the fuse to measure its resistance. A good fuse will show continuity, meaning the filament is still intact. If the fuse is blown, there won’t be continuity. In simple terms, if the multimeter beeps then your fuse is ok. If it doesn’t then you need to replace the fuse.

5.Replace the Blown Fuse

After finding the blown fuse, you must replace it with a new one. The new fuse must be the same size and must also have the same amp rating. If you put a weaker one, it will blow right away. If you put a fuse with a high amp rating, it won’t blow. But you will be risking the entire circuit board. So, to ensure you replace the right one, look at the fuse diagram under the fuse box lid.

How to Prevent the Fuse From Blowing Again

Fuses usually blow because they are overloaded. So, before adding a new accessory to your RV, van, or boat, find out if the fuse can support it. Also, make sure the fuses replaced during the servicing are the right ones. If you have a fuse that consistently blows, take the vehicle to be inspected for other faults.

How to Replace the Fuse In My RV

Fuses in RVs and cars usually work the same way. This means that you will get the same telling signs when one blows out. However, the location of these fuses and how many there are is what differs. Most RVs and vans use both AC and DC. Both functions have different fail-safes in the event of a surge in current.

For AC-run electronics, a circuit breaker is used in place of a fuse box. These are quite similar to the ones found in houses but much smaller. For DC-run electronics, there is a typical fuse box. Fuses for larger RVs or motorhomes are distinctly different from the ones you’ll find in a normal car.

If you are watching TV or cooking in your RV and you lose unexpectedly power, chances are high that you have blown a fuse. The procedure for replacing it isn’t any different from that of a car. Locate the fuse box and replace the blown fuse with a new one. When replacing these, make sure you stick to the right amp ratings.

If you put a weaker one, it will blow right away. And if you put a much stronger one than the system requires then you are risking the entire van. We also recommend you carry extra fuses before you drive off for a trip. There are so many fuse kits sold today but always aim for those in the range of $30. These are usually of much better quality and will ultimately give you value for money.

Conclusion

While a blown fuse can be a source of frustration, it’s insurance for the power circuit and the entire RV, boat, or van. Hopefully, our guide has given you the much-needed insight into what fuses are, how they work, and how to tell if a fuse is blown and replace it.

Frequently Asked Questions

Is a blown fuse a symptom of a bigger problem with the vehicle?

Yes, especially if it happens repeatedly. When a fuse blows a couple of times, that can be an indication of other delicate issues like an electrical short circuit, overloading, or a malfunctioning component. Reach out to an electrical engineer for a deeper diagnosis to rectify the problem.

Do RV batteries need fuses?

Yes, they do. Most energy storage batteries used in RVs, vans, or motorhomes have main fuses. These are designed to protect the batteries and wiring in case there is an overcurrent flow. There’s a common misconception that lithium-ion batteries are safer than conventional lead-acid batteries.

However, they can still cause a surge in current which could damage the RV and the electronics. For complete safety, use a main fuse for all your batteries to protect the main system.

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