spedo reading "funny"

[thedeal]

Sorry for the double post but I thought I might get more views/responses here.

I have a Canadian 1990 E30 and I swaped the instrument cluster. When I installed the US standard version both my tach and spedo read below the norm. At idle my tach reads appx. -2000 and my spedo at 35 mph reads appx. -10. What in the world happened? can I adjust this. Also, how do I reset the mileage back up to the actual mileage on my vehicle?

Thanks

The tach has now righted itself, but the spedo reads appx. 45 mph off.

The spedo i replaced it with is a motronic, the spedo prior to that was a VDO. Any help would be much appreciated.