How to Find a Car's Main Battery Fuse

Video Transcript

"Hi, I'm Aaron Gregory on behalf of Expert Village, and we're going to talk about what happens when your car battery dies; how to select a new battery, and how to see what the problem is. Now when your car won't start, there's a lot of things to check. The main fuse in the fuse box under the hood is one of those things you should check when there's no electrical power. We're going to open the fuse box and try to find the main battery fuse that controls the voltage from the battery to the electrical control center and distributes electricity throughout the car. When there's no clicking from the starter and the headlights don't work; that can be a dead battery or it could be a wiring problem. This fuse box has a nice label on top, and I've found the main fuse here and it says "battery" and it says "70 amps". So I'm going to look underneath that little sign for that fuse. Lots of interesting stuff here in your fuse box under the hood. Your owner's manual should be able to tell you where the fuse box is. There's usually a separate fuse box inside the car under the dash for accessories. The electrical controls couldn't be much simpler or more clearly identified. You see here it says "main fuse" and there's a separate cover and another separate cover that says "main fuse". A fuse is a small link of wire usually contained in plastic or glass and it has a number on it; that number is the amperage rating. If it says "10", it's a 10-amp fuse. SO any electrical draw over 10 amps will blow the fuse so as not to cause a wire to melt somewhere deeper in the wiring harness. Fuses are easy to replace and easy to test. If we look under the main fuse cover, we should find a fuse with a window that allows us to view the wire filament. If it's intact; it's probably O.K., but it can be tested. This is a small, standard automotive fuse; usually these are used in all cars, probably fifty or more of these fuses. As you can see, there's a loop of wiring leading from the left leg to the right leg; this allows current to flow. This fuse looks to be intact, but there's a way that I'll show you how to test with an electrical tester. This is not the main fuse for the car, though; let's take a look at that. Here's the main fuse cover, easily identified by the words "main fuse". Now using the lid to this electrical box as your guide, you can figure out where the battery fuse is; it looks to be under this cover. So let's snap this out, and set it aside and compare this top guide "main fuse battery 70-amps". Now these five look to be here. Now this is going to be electrically hot/charged on one side once the battery is connected, so don't poke around in here with anything metal. Here's the battery fuse, it says "70-amps" on it. I know it's the battery fuse because I compared it to the indicator here on the lid. There's a small window and a small copper bridge that's where all the current gets to the car through this copper bridge. If it's burned, the car will act like it has a dead battery."