Just curious to know what this "codes plug" according to haynes is for? It has two wires going in, a brown and a brown w/ white strip If you couldn't tell from the picture (sorry for bad quality and not circling, but I am at my parent's house) it is coming out of the computer's main harnness I have only heard of the test port under the hood before I pulled the computer out, does it give the same info?

thanks

scular