What Does A Fuse Do Exactly?
Motorcycle fuses, like car fuses, are essential components of your electrical system. The fuse helps control the electrical current from the battery to specific systems. It protects the electrical components from surges and overloads from faulty wiring or when the circuit exceeds its limits. Blown fuses are a way of signaling that there is a problem with your bike’s electric circuit.
Think of a fuse as a lifeguard of your electrical system. A fuse constantly monitors the flow of electrical current to a component, keeping its power level stable. But if something unforeseen happens, and the situation warrants, the fuse will blow (give its life to keep the surges from frying your system just like a lifeguard will face a riptide to save a drawing swimmer). A fuse is designed to give itself up before allowing harm to your components.
Why Does A Fuse Blow?
When a fuse blows (stops working), it breaks the connection between the battery and the component (lights, fuel injection, ignition, etc.). The inner workings of the fuse (a small curved metal strip inside the plastic casing will be broken or look burnt. The broken strip indicates some extra load on the system that caused the fuse to give itself up rather than open the door and do untold damage.
Motorcycle fuses blow for a variety of reasons, but they always indicate an electrical problem of some kind.
- Electrical surges
- Overload of electrical circuit
- Short circuit
- Accessory device failure
- Fuse failure, corrosion of fuse box, or fuse age
- Faulty connection
Fuses can also fail if they are old, vibration makes them lose contact, or if they get corroded. So, the fact that your bike has a faulty fuse doesn’t always mean that the fuse isn’t good; it might have just come loose in its receptacle and lost contact with the energy flow. A careful inspection of the fuses can determine if your fuse needs to be replaced.
How To Identify And Change A Fuse.
Here are some step-by-step directions for replacing a bad fuse.
Turn Your Bike Off
While replacing a fuse isn’t a hazardous proposition, you don’t want your bike’s power source engaged (turned on) while messing around with the electrical components. Turn the ignition switch off.
Locate The Fuse Box
Fuses are inside the fuse box that is located directly under the seat on a motorcycle. You will have to remove the seat and open the fuse box. You may have to use a flat-blade screwdriver to remove the cover. Remove the fuse box cover to get access to the malfunctioning fuse. Some bikes will require removing the entire fuse box to have access to the fuses. If this is the case, we would recommend that a certified technician be hired to trace the wiring, and test and replace any damaged components.
Find the Bad Fuse
(The first glance at all the fuses can be intimidating, but have confidence, you’ve got this). Your owner’s manual will have a fuse box diagram that will aid in identifying which specific fuse corresponds to each electrical component. This information can help you zero in on the faulty fuse without disturbing the other fuses that are working correctly. For example, headlights are on different fuses than ignitions, so if your headlights aren’t working, check and pull the fuse assigned for that component.
Pull The Fuse
Once the appropriate fuse has been identified, you will need to pull out that single fuse with a pair of needle nose pliers. (We don’t advise using your hands because your fingers might bump the other fuses or not get enough grip on the lousy fuse to muscle it out. Sometimes they can be wedged in pretty tight).
Visually inspect the fuse. Hold the fuse up to the light to see if there is a break in the thin metal shape (the round part) inside the plastic housing. Fuse covers are clear enough that you should have no trouble assessing this issue. A lousy fuse will have a broken strip, while a good one will have an unbroken connection.
In addition, other signs can be burn marks near where the fuse is connected to the electrical grid. If you discover the fuse is blown again and after replacing it, the fuses are not the issue. (You have more significant problems on your hands).
Check the New Fuse Amp Rating
Almost every fuse has an amperage rating printed on the end of the fuse. (often a 10, 20, or 30). Ensure the fuse you plan to insert has the same rating as the old one. If you don’t use the same fuse as the one you removed, the wrong fuse can spell disaster for your electrical system and the bike components.
New fuses can be purchased online or at any auto parts store. Most motorcycles come with extra spare fuses. (Some fuse boxes will have a spare fuse or two near the fuse box, but not always. Look for a fuse holder near the battery). The manufacturer provides these extra fuses if you blow a fuse while cruising down the road and need immediate repair.
Insert the Replacement Fuse Into the Socket
Insert the new motorcycle fuse into the socket and gently press down until the fuse clicks into place. The fuse should be firmly in place, with no wiggling or movement. When replacing a new fuse, check to ensure the other fuses are secure. (Just tap down on the top of the other fuses to make sure that the others have stayed put during your removal of the lousy fuse).
Refasten the Fuse Box Cover
You will need to refasten the fuse box cover, replacing any screws that you had to take out to remove it. Reposition the seat and reinstall the seat bolts, and fasten it into place.
Test the Electrical Component
Start your bike and test the component. If the fuse blows out again within a short period, this situation is an indication that you have something else wrong. Some kind of electrical fault is creating an overload of the electric circuit. (A short or faulty ground connection is often the issue). If this happens, it is best to take the bike to a certified technician who can diagnose the faulty system before it creates serious electrical damage.
How Many Fuses Does A Motorcycle Have?
A typical motorcycle has between 7 - 15 fuses powering all sorts of electric accessories. There is a main fuse that looks different than the other fuses and is usually separate from the rest of the fuses in the box. All electrical current routes through the main fuse (except for the starter), so a faulty main fuse could be the problem. (If the bike is not starting). Consult with the wiring diagram in your owner’s manual for the exact location of the main fuse. You can diagnose a bad main fuse with a multimeter.
Can A Fuse Failure Keep My Battery From Charging?
A broken fuse can keep your battery from being able to hold a charge. While other reasons (a faulty ground, corroded terminals, or bad stator or alternator) can also create the issue but fuses often play a role.
Is A Bike Fuse The Same As A Car Fuse?
Yes, the fuses that your car uses and the ones that power the circuit of your bike are the same. They can be used interchangeably. If you have a package of fuses on your workbench that you bought for your car, you can use them as a motorcycle fuse. (Just make sure that the amp ratings are right).
About THE AUTHOR
Russ currently owns a Yamaha FZ6N and KTM RC 390. When it comes to vintage bikes, his favorite motorcycle is the feisty BMW R32. He also holds a particular interest in the LAMS segment and triple cylinders. Himself a riding enthusiast, Russ has had experience with racetracks from around the world including Willow Springs Raceway in California and the Imola Circuit in Italy.Read More About Russ Crowley