I've had my swap running well now for close to 10 years. I finally decided to tackle getting the final codes out of the system by trying to install a rear o2 sensor. I plugged in my scan tool to see the codes and it says no communication from it now. It used to work but something happened recently. I tried 2 of my other scan tools and no go. I took it to Autozone to see if they could scan it and the guy didn't have much luck either but said he it almost worked when he was wiggling the thing around.

So I took OBD2 port out. I traced the wires to the computer, seems to have continuity on pin 2 of the OBD2 connector back to the ECU. The two grounds seem to be ok using my test light. I seem to have the proper power.

I did notice the metal connector was a little green, would that be enough for it to cause a communication issue? I tried scrapping it but no luck. The truck runs like a champ so I don't think the computer is dead. I cleared the codes by pulling the battery, and the MIL came back after 10 minutes of driving. I just ordered a cheap scope and a new OBD2 port. Anything else I could do?

Is there anything else I that i may have missed or something that would cause this to randomly stop working?

 

The green you saw in the connector is corrosion, which isn't good for good electrical contact.

I would start by installing the new OBD2 port (with nice, shiny ,new terminals) and go from there.

Do the terminals at the ECU look nice and shiny?

 

I didn't look to hard at the ECU side since it's such a pain to get to on my rig. I'll pull the harness out of the ECU and see what I see. Thanks!

 

Try running separate wires from the O2 sensor connector to the backside of the ECU connector... use the scanner with live data feature to see if the ECU see the voltage between 0 and 1V.

 

Well his current issue is he can't get the scanner to connect so that's a problem that needs to be tackled first.

 

The serial wire (shielded white) from the ecu is not on the right pin out of the plug. Was the obd2 port out of a Toyota vehicle? I know I had to rob mine out of a Chevy and re-pin it to work.There should be four wires, two grounds, one 12v and the signal wire.