Where's the Diagnostic plug?

[cosmic_splatter]

Folks I'm put a deposit on a 1995 Geo Tracker. It has a check engine light on and we were trying to obtain the code, but there doesn't seem to be a diagnostic port. The connector seems to be plugged into a cable as shown in the photo.

Anyone have any thoughts on this? This does not correspond with the B-C pin shorting tutorials on the internet.

http://i957.photobucket.com/albums/ae59/...b5a086.jpg

thanks,
John