Hi,
There has to be a wiring issue. Check pin 7 (k-line) for damage or condition. If you look at pic 1, I highlighted the k line to the PCM. You will need to check it at the PCM as well. This is part of the CAN system. (computer area network). To test it requires a can scanner. Without one, you would need an oscilloscope. Check to see if the wiring at either end (DLC or PCM) is corroded or damaged.
Here is a link you may find helpful:
https://www.2carpros.com/articles/how-to-check-wiring
Let me know what you find.
Joe
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Wednesday, December 23rd, 2020 AT 11:29 PM