Problem reading with OBD

I have a friend trying to pull codes on a 96XJ and he has taken it to several places. All three places said they could not get any communication between the OBD port and the scanner. Is there any reason why this is happening or does it have more than one port? The one he has been trying is under the dash. He is just trying to get the check engine codes read, I also told him about the key on, off, on, off, on way to check it. Any help would be great. Thanks

Sounds like he can drive it, so drive it around and get it nicely warmed up. Shut it down, then switch ON (not start), OFF, ON, OFF, ON and wait a few seconds for the Check Engine light to come on. At the very least it should flash Five-Five indicating no stored codes. I've heard some reports that ON, OFF, ON, OFF, ON, OFF, ON may be required to get it to work.

Find out which fuse powers the diag port and check it.