Sounds like you used to be an '02er..the ground on E-30 dash and instruments is carried in a pair of connectors of flat cabled and otherwise bundled wires that plugs into the back of the cluster. I do not remember exactly how the guage itself picks up ther connection in the cluster, but it will be self-evident when you pull the cluster and take it apart. I had the same trouble with our 325e till i took it apart, and just put it back together. (Change out your SI board batteries while its apart..(see other post today Re; Batteries..yes, the Radio-Shack Ni-Cads work fine)It worked ok after that. You may have a sending unit problem, also another post today.. Good luck!