I have a 1999 5.9 Durango. It was working fine till I removed the dash to repair the ac blend door. Now after I put it all back together the OBD2 port will not link up to scanner. It has 12 volts at pin 16 so its not any fuses. I've checked all the visual grounds. I've traced all the wires from the OBD2 port back to the PCM harness and everything was good. I sent the PCM to a repair guy & they said it checked out ok.. I'm stumped.!!! Anybody had this happen to them? Any fixes.?? Thanks...

 

does the scan tool power up and not communicate or not power up at all?
-pin 4 is chassis grd, pin 5 is signal grd...check them for continuity to grd
-try another scan tool
-check for voltage on the communication pins...not sure what pins are used for your build