No Communication

What would cause my diagnostic port to not work. SES light came on recently, and when I hook up my scanner, the scanner does not come on. However, it sounds like the fuel pump is priming while it is plugged in. The car is a 96 OBD 2, and has a mail order tune. Also I have checked all the fuses. any suggestions?

Also, prior to the SES light coming on, the car ran like crap obviously. It would cut out, and sputter above 3000 rpm. however, as soon as the SES light came on, the car started running "normal" again.

If your scan tool is battery powered, you might check the batteries.

The port is on the same circuit as the cig lighter. Recheck the fuse.

thank you very much for the heads up on the cig. lighter fuse. there was a 20A fuse in there - supposed to be 25A. obviously it was blown. Scanner now works, O2 sensor was bad. Thanks again, I feel like a jack ass.