Update:

I disconnected the instrument cluster again to back check some wires.

The blue connector from the Instrument cluster at Pin 20 goes to the interior lights. I measured 0.8 to 1.2 ohms to ground. This is going through light bulbs all in parallel, about 10 lights as best I can tell from the wire diagram, and if they are about 5 watts and if are running on 12 v, then the resistance expected would be about 1 ohm or so.

I went through the exercise (and I do mean exercise) of unplugging the connectors going to the drivers side door. and this value did not changes much at Pin 20. So I don't think there is a short in the drivers door wire harness. (it was a FRIGGEN PAIN IN THE A&& to get at those plugs, as the panel that covers them is captivated by the dashboard along the side, instead of being easily removed, dumb design, and the connector have two snaps that have to be simultaneously bent out....you get the picture....) By backing the wires out of the door frame I got a better look at their condition and there are no breaks in the insulation noted.

I checked the continuity to the wire running to the dimmer, Pin 30 on Green connector, and that was fine, no shorts to ground.

I checked the function of the dimmer Rheostat itself and got a range of 0.3 ohms to 8.50 K ohms (same for my original dimmer switch), so that is working correctly. I verified that the ground to the dimmer switch was actually connected to ground.

I think it's time to give up and either live with it they way it is.....or take it to the dealer for a look as they have better diagnostic tools at their hands.

If I have the new instrument cluster installed by them, and it fries also, then I am set back the cost of that second hand part. If I let them order a new one from Germany and that new one fails then they are on the line for that cost.

Mike