Replacing harness?

Browsing craigslist I've stumbled upon an MJ that looks pretty nice and it seems the harness needs to be replaced. I have no idea what this means, or entails, so if someone could enlighten me that would be awesome. The new harness is included, do you think it would be difficult for a total nub to replace? Thank yall.

Depends on which harness dash or under hood. If it's the dash once you get it out it's extremely easy to replace, the under hood harness is a little harder but if you lay the new one in place and go one connector at a time can be done without to much trouble.

He seems to believe its a wiring issue with a short occurring somewhere, if that helps determine which harness it is.

Sounds like he's thinking the under hood harness. Depending on the problem and symptoms we can help you figure out what it is as it might not be the harness.