Subjects:
- Introduction
- Standard fuse
- Mini fuse
- Maxi fuse
- Cartridge fuse
Introduction:
During diagnosis, it can be useful to check the voltage drop across fuses. The current flow through the fuse affects the voltage difference at the contact surfaces of the fuse because the fuse behaves like a (small) resistor. This resistance causes a voltage loss as soon as current flows through it. The higher the current, the higher the voltage loss. We can use the magnitude of the voltage difference (= voltage drop) across the fuse for diagnostic purposes. By measuring the voltage drop while connected, we can determine if current is flowing through the fuse. Depending on the type of fuse and its nominal value, we can look up the current flow in tables. These tables are displayed on this page.
Explanation on reading the tables:
After measuring the voltage difference across a fuse, we can look up in the table how much current is flowing through it.a0
- Measured voltage difference: 1 mV (0.001 V)
- Type of fuse: ATO, red, 10 A
- Current flow through the fuse: 130 mA (0.130 A)
Standard fuse:
In passenger cars, we usually find blade fuses in the “mini” and “normal,” or standard sizes. The standard blade fuse is coded as “ATO”. An example can be seen in the next image, showing side, top, and front views of a red 10 Amp fuse.
The tables below show the voltage drop across the fuse. The voltage drop indicates how much voltage is absorbed in the fuse. The voltage drop depends on the current flow through the fuse and its blown-fuse safety.
Mini fuse:
Besides normal ones, we also find mini blade fuses in passenger cars’ fuse boxes. The mini fuse is, as the name suggests, a smaller version of the normal fuse. An example is shown in the next image: this is a violet fuse with a blown-fuse safety of 3 Amps.
The two tables below show the voltage drop across different fuses with increasing current flow.
Maxi fuse:
The maxi fuse is the largest type of blade fuse found in passenger cars. This type of fuse is suitable for high power applications.
Cartridge fuse:
This type of fuse is often found in Japanese and Korean cars. The cartridge fuse consists of a square plastic housing with a transparent cover. The housing can be long or short. The melting wire can be seen through the transparent cover, indicating whether the fuse is still intact.
The tables below show the voltage drop across this type of fuse.
Related pages: