Random loss of OBD2 Communication while engine running

[William]

alright, where do I begin? I am having random loss of communication to the OBD2 port while running, on my 1998 Chevy Tahoe 2wd LS. (350 5.7 V8) Here is all the stuff I have done,

1. Swapped ECM (Junk Yard ECM For testing)

2. Checked connections on ECM while running (Wiggled them, pulled ect)

3. I did have a bad O2 sensor which I swapped out today.

4. checked under the truck for any lose wiring harnesses, corrosion, rust, ect.

5. checked Fuses, relay’s, Power, grounds

6. Had about 2 different shops look at it, so far no answers.

7. I did wiggle and move around the wires that go through the firewall to no avail.

conclusion, Everyone keeps telling me the ECM is bad, well, that was proven wrong to me by swapping it.

I can’t pass an emissions test because of this. Is there anything I missed? I’m completely Out of Ideas at what to do at this point. The truck starts right up and runs great and drives perfect.

Topic

[David]

Check pins on obd2 port or even spray the port with some electrical spray to clean port out.

[William]

Cleaned the OBD2 port. Still have the problem.

[Richard Kirshy]

Just a thought..
If your 1000% certain the issue is not the ECM.
If your 1000% certain the issue is not the wiring.
Have you check for pin fitment issue(s)

[Author]

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