I've got a 2003 that I'm installing a stereo into. I got a harness from Crutchfield, but the plug seems to be missing a wire (see attached image).

There is indeed a wire on the chassis side of the plug (its grey). Is this a problem? Whats the grey wire go to? On the old harness thats there now, there is a black wire coming out of that spot going to a black wire on the old headunit.

Any help is appreciated! This is my first stereo install, but I am a little familiar with wiring (wired up all the stuff for my nitrous kit... its ugly, but it works! lol)

 

Just FYI, I went ahead and connected everything, and the headunit worked fine!