Originally Posted by Fabrik8

IAT is intake air temp.

If you can visibly see that the harness has been hacked up enough that you don't trust it, get a new harness. Nothing is a bigger waste of time than trying to troubleshoot a problem based on wiring that is improperly done. If you don't know what the starting point is, it's really hard to gets results. On an OEM harness, you know what it SHOULD be like, and then you can find out what's different and what's wrong. On a totally hacked up engine swap, you probably have no idea what you're starting out with, so you basically have to redo everything yourself just to know what your baseline is for troubleshooting.

Think of it this way: Say your time costs $10 or $15 an hour. If the time it will take to troubleshoot the old harness is more than the cost of a new harness, get a new harness. I think about a lot of stuff that way. It doesn't really make sense to spend a shitload of time doing something that isn't that expensive to begin with. I know people who spend 10 hours trying to fix a $50 part, and I'd rather just buy a new one and go to into work for a few extra hours to cover the cost. They'll say that they saved $50 because they didn't have to buy a new part, and I say that I didn't have to waste 10 hours of my life fucking around trying to make an easily replaceable (and relatively cheap) broken part work. I know people say that their time is free because it's their car or whatever, but they can be making a lot of money doing something else in that "free" time instead. Sorry, off on a tangent there.