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Key Motorcycle Fuses & Troubleshooting
Here are the four most common fuses used on modern motorcycles. Each section includes dimensions, a brief description, a line-drawing illustration, and notes on typical faults.
Standard Blade Fuse (ATO)
Dimensions: 19.1 × 18.5 mm
Overview:
The most widely used fuse style on motorcycles since the 1990s. Plastic housing with two flat metal prongs that insert into the fuse block.
Mini Blade Fuse (ATM)
Dimensions: 10.9 × 16.3 mm
Overview:
A compact version of the standard blade fuse. Ideal for tight spaces in modern fuse panels.
Glass Tube Fuse
Dimensions: Ø 6.3 × 25/30 mm
Overview:
A cylindrical fuse with visible element and metal end caps available in 25 and 30mm lengths. Common on older or vintage motorcycles.
Continental Fuse
Dimensions: Ø 6 × 25 mm
Overview:
A sealed, inline cartridge fuse used on Continental-spec wiring harnesses. Screws into a holder for quick replacement.
Fuse Ampere Color Codes
Standard & Mini Blade Fuses use the following color scheme:
| Amperage | Color |
|---|---|
| 2 A | ● Grey |
| 3 A | ● Violet |
| 4 A | ● Pink |
| 5 A | ● Orange |
| 7.5 A | ● Brown |
| 10 A | ● Red |
| 15 A | ● Blue |
| 20 A | ● Yellow |
| 25 A | ● Clear/Natural |
| 30 A | ● Green |
Common Faults by Fuse Type
Standard Blade Fuse (ATO)
- Blown Element: Caused by overload or short circuit.
- Housing Cracks: Vibration can crack the plastic, allowing moisture in.
- Corroded Contacts: Poor seating leads to high resistance and heat build-up.
Mini Blade Fuse (ATM)
- Overheating: Loose fit in aged holders can cause heat.
- Element Fracture: Repeated load spikes may break the strip.
- Oxidation: Corroded contacts cause intermittent failures.
Glass Tube Fuse
- Moisture Ingress: End-cap seals can fail and corrode.
- Element Break: Sharp shocks may snap the wire.
- Pitting Marks: Arcing leaves tiny craters on the glass.
Continental Fuse
- Loose Mounting: Vibration can unscrew the holder, breaking contact.
- Seal Deterioration: Rubber gaskets age and admit dirt/moisture.
- Thread Wear: Frequent swapping wears threads and reduces clamp force.
How Motorcycle Fuses Work
Fuses are sacrificial devices that protect electrical circuits by melting their internal element when current exceeds a safe limit. This interrupts the circuit, stopping excessive flow and preventing wiring damage, component failure, or fire.
Common Fuse Fault Symptoms
- No Power: Blown fuse cuts power completely to a circuit.
- Intermittent Power: Corroded or loose contacts cause flicker.
- Excess Heat: High-resistance connections heat the holder.
- Frequent Blows: Indicates underlying short or overload.
Troubleshooting & Maintenance Tips
- Always replace with the exact same amperage rating.
- Inspect fuse holders annually for corrosion and cracks.
- Use dielectric grease on contacts to repel moisture.
- Secure inline holders and harnesses against vibration.
- Carry spare fuses and a puller on long rides.
