I own a 2003 chevy p/u w/4.8 auto and recently had my truck checked for codes at the local Auto Zone due to a possible misfire, (but no ck. eng. light is on) to be pro-active before inspection. The guy said the scanner wouldn't read my OBDII port. I have no mods on my truck...(ie. aftermarket pcm) Can anyone plz help!!!

Scratch that guys...sorry. I obviously didn't read enough of the other related forums. My cig. lighter fuse hasn't been in since I installed aftermarket radio... duhhhh!!!!

 

Check your cigarette lighter fuse. It's very common for them to be fried. I've even seen brand new trucks with popped fuses.