How to Diagnose a Common Problem in GM Truck Fuse Boxes

Are you having problems with your Chevy or GMC truck? Let's talk about a probable reason why.

Hey friends, it's Len here from 1A Auto. Today I want to talk to you about a place that I would look if I was having electrical issues with my GMC pickup. If I was to come right underneath the hood, to the fuse box that's located on the driver side, we're gonna go right here and take a look.

Let's grab right onto this cover right here and lift it right up. You can see that's where the fuse is going to be. Once you lift this up, you're more than likely going to see something that looks a lot like this. It looks as though the fuses and everything are covered in some sort of oil or grease, or I don't know what somebody would put in there, but in all honesty, that's not actually something that somebody did, it's actually more of something that something did. If you were to look right along here, you're gonna see a nice clear passageway that leads up in there. And then if you were to look down along the side, which is where I'm gonna lead you next, you'll see where the perpetrator is gonna get in. So what happens is, it makes its way up in here and then decides it wants to urinate. As it urinates, It's gonna to make a mess and it's going to obviously cause very big issues in areas that you can see. Something you want to pay attention to is right underneath these fuses. Yeah, you can see that up along the top. They are definitely contaminated with something and that's very bad, but the main issue would actually lie underneath all these fuses. Underneath here you're gonna see something that looks a lot like a circuit board and you can imagine what it looks like. It's gonna have all sorts of different connectors going from one place to another. And they're supposed to support electrical current. The fuses of course are supposed to blow in between in case there's some sort of circuit issue. When the circuit board gets this type of crud on it, whatever it might be, whether it's pee or some kind of contaminant, it's gonna obviously cause corrosion and major issues down the line. If you look right up along here, you might even see some type of insulation or anything else that somebody tried dragging into this area. We're gonna lift this box up and take a peek right under there.

Go ahead and grab this cover, lift it right up. Holy moly. We can see that we definitely have a nest going on in here. As you can see, that's a nice place that a mouse would want to get right up inside and having this nice cover over it is going to protect the mouse from pretty much anything that might try to get to it. And it makes a nice comfy home for it. So it comes up in here, it makes its nest, brings in all this crud. And of course any of that could cause an issue, especially if it's holding moisture along the bottom side of this. Take a peek under here. Oh, wow. Looking under there, I can see it definitely looks like somebody is making a nice house under here. That leads me to believe that there's probably a mouse or maybe even a small squirrel. Anyway, the next thing I would want to do is check around. I want to take a peek at everything and check these wires. Make sure that they don't look as though they're getting chewed on or broken in any way. Oh boy, there's one right there. If you see wiring that looks like this, it's obviously very bad. Wiring that looks like this that's exposed could ground out. It could cause resistance. Overall, you might notice that your vehicle runs funny, it doesn't start at all, your check engine light turns on or even just some of the electrical stuff inside the vehicle starts acting fluky such as your wiper blades working on their own.

So now if your fuse area looks like this and it's full of contaminants, whether it's on top or down bottom and maybe you even have wiring issues, pretty much the best way to fix this would be to actually replace the unit. You'd wanna replace it because cleaning it out, you might get the top nice and pretty, but how are you gonna to get to that circuitry underneath?

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