I have 2004 AT TL with 220k miles on it

I started to hear knocking noise (30 to 40 times and it stops) from under steering wheel. it has nothing to do with driving performance

It happens when I turn the ignition key to On(ii) or while driving (most of time when I start the car in the morning).

I think it's a electrical problem because noise occurs even engine is not started.

And The noise and vibration are coming from part (I think it'a called PCM connector) that is related to odometer.

When I plug out the connector (it's green square shape connector located right side) it reset the traveled miles to zero but noise and vibration also stops.

Does anyone have any idea what this problem might be?

Any suggestion would be appreciated