Disconnected electrical cable?

Could you take a picture of it and post it here please? The battery in that year is supposed to be on the passenger side and the battery cables are short to connect to it. No cables go over the engine unless someone altered the truck. That is where a picture would help. The attached are the 2.0 4 cylinder and the 2.5 v6 to show the stock layout. Do either look correct?

Battery is on the passenger side, but cable comes from driver... My mistake.

Not a factory cable, looks more like something installed for an amp, or possibly a plow. Single 10-gauge wire is common for that. That is a well-done install, I would look under the dash for the other end. It's likely not connected if they pulled those parts out, would let you install something if you wished. I ran wiring like that on my POV when I was with the FD. Used it to power the radio gear and the lights.

Interesting. Still hooked up under dash, I had someone tell me it was for the car's computer system, so he connected it back to power. Should I disconnect it?

Here's the hook up. There's a service engine light on, guy who I bought it from said it's been on since he bought it. I wonder if the cord is why.

Move the wire out of the way and I'm betting you will find that module isn't factory. It looks like a remote start or alarm module zipped tied into place.