i was cleaning my car and i looked under the dash under the steering wheel and i saw this plug and i dont know what it is for
 
there are a ton of plugs under there, but you're probably talking about the data link to the pcm...
 
PCM connector, not to be confused with the joystick connector 
 
 
 
 
More than likely its the on-board diagnostic port... is it one shaped kinda like 
_________________________
\ .......................  /
.\ .....................  /
.  \_____________________/
(pardon the dots... vbulletin don't like a lot of spaces in ASCII art)
 
 
all of which are what I said 
