Step by step guide on how automotive fuses work. This information pertains to all vehicles.

Step 1 - A fuse protects a circuit from overloading in extreme operating conditions or in the event of a short circuit. Most fuses are located in the vehicle's power distribution center.

Power Distribution Center

Step 2 - Inside the PDC are many heavy and light duty fuses which protect various circuits which demand a specific amperage.

Heavy w/Light Duty Fuses

Step 3 - All fuses are designed with an element which will melt if the circuit amperage exceeds the fuse rating.

80 Amp Fuse Element

Step 4 -  A fuse is typically defined by the amperage rating its designed to protect, such as this 30 amp fuse.

30 Amp Fuse

Step 5 - Fuse power is supplied by the positive battery cable which is attached to the positive side of the battery.

Fuse Power Feed


Written by
Co-Founder and CEO of
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2015-01-07)