Won't connect issue?!

[hotrod]

Went to pull a tune off a 2006 Chevy truck with a 5.3 and here's what happened.
I have my flash scan hooked up to my laptop and as soon as i plug it into the OBD2 port the flash scan goes dead, screen goes blank. The same thing happens when i hook up my tech 2 as well, screen turns on but won't boot up.
I verified the both my flash scan and tech 2 still work on another firebird i am working on.
So does anyone have any ideas? I checked both ground on the plug and they are good, has power as well. I'm lost on what to look for?

[joecar]

Your truck's OBD-II has a power wire problem... you need to find the wire diagram and probe the port with a DMM.

[hotrod]

That was it. Just ran a new hot wire to the fuse box and it works like a charm.