I have a 87 GTA swapped with the 3.8 liter turbo engine installed. I have the full inst. cluster with al gauges working except speedo ( waiting on VSS sender)and I cant get the tach to work. I have an accurate tach reading on my scanner and I have voltage to the white wire when I pulled the cluster; is there any test to apply voltage to that little ribbon circuit and see it the tach really works? Any other suggestions?