4 Facts About Automotive Fuses

Automotive Technician Evans Tire

Your car’s fuse box is a safety system for your car. When there’s a short or other issue in an electrical line, the associated fuse burns up so your auto wires don’t. Here are four other things you should know about your automotive fuse box.

  1. Fuses Are Located in Various Spots

The owner’s manual that came with your vehicle will show you exactly where to find the fuse box in your car. The fuse box includes the fuse block, into which the fuses are connected, and the fuse-box cover, which protects the fuses inside from debris, dust, and moisture.

In some vehicles, there are two fuse boxes. A heavy-duty fuse box is placed under the hood to protect headlight and AC wiring while a smaller fuse box is installed inside the vehicle to protect accessory wiring. Access doors to interior fuse blocks may be rectangular or circular in shape depending on the make and model of vehicle. Typical places for interior fuse compartments are:

  • In the driver-side door panel
  • In the end panel of the driver-side dashboard
  • Under the glove box
  • Under the dashboard

The location of the fuse box under the hood varies by make and model. The car may also have auxiliary fuses if extensive modifications and electrical upgrades have been made.

  1. Fuse Boxes Offer Help in Several Ways

Most fuse-box covers are easily removed with a clasp. When you take the cover off of the fuse compartment of your vehicle, turn it over. In most vehicles, you’ll find a diagram of the fuse block printed on the underside of the box cover.

The diagram shows you the location of all fuses in the block and tells you which parts or accessories each fuse protects. Some fuse locations may be empty, and the diagram will show you that this is okay. All fuses noted on the diagram should be in place in the fuse block. If fuses are missing, consult your auto service technician to find out why. Repairs and other modifications may have made those fuses unnecessary.

The large gray or black squares plugged in to the fuse block are not fuses. These are relays. They protect components from voltage drops between the power source and the electrical part. They can also wear out and require replacement by your mechanic.

Inside the fuse box is another helpful tool. A small plastic fuse grabber is included in most late-model vehicles. Don’t try to pry plastic fuses out with your fingers or pliers. The grabber tool makes the job much easier.

  1. Fuse Types Vary by Make and Model

Most modern vehicles use blade-type fuses. These fuses are made with two metal blades that insert into the fuse block. The top portion of the two blades is surrounded by plastic to protect a tiny wire running between the blades. That tiny wire is the part of the fuse that breaks or burns out when your vehicle has an electrical issue. Some fuse wires are S-shaped, some are arc-shaped, and some run straight from blade to blade. Blade-type fuses are available in four basic sizes:

  • Regular
  • Maxi (for higher amp applications)
  • Mini
  • Low-profile mini

Each of these blade types has its own color code to indicate how much amperage the fuse can handle. If your car has a windshield wiper issue, and if you notice that the windshield-wiper fuse has blown out, you must replace the fuse with the same color and amp-rated fuse.

Always double-check that you have the correct size and type of fuse before inserting it into the fuse block because different cars require different types of fuses. These fuses may be encased in glass, ceramic, or plastic housing. Your mechanic can order most of these fuses for you.

  1. Fuse Replacement Doesn’t Always Fix the Problem

If you must replace a blown fuse, be prepared for the same fuse to blow again. Most of the time, a burnt fuse indicates that something is wrong with your vehicle’s wiring or electrical components.

It’s also sometimes hard to tell if a fuse is actually blown. For example, even though the plastic on blade fuses allows you to see the sacrificial wire, the fuse may look intact when it’s actually not working.

Your mechanic can check the current on top of the blade fuse for you. On either side of the plastic fuse top is a small testing spot corresponding to the blades. If only one spot lights up with the tester, and the other side does not light up, that fuse is blown.

Whatever type of vehicle you have, a professional mechanic will know exactly which fuses your car needs and how to diagnose wiring and fuse issues of all types.

Contact the automotive experts at Evans Tire & Service Centers today to schedule an inspection of your vehicle’s fuses. We service cars, trucks, and SUVs seven days a week in the greater San Diego region.

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