The chassis ground point(s) you speak of, is one of them near the front headlights? I did install Euro headlights the other weekend and noticed a group of brown wires connecting to a stud. Is it possible that I pinched a couple while installing the headlight(s)? I don't remember having to "juggle" those wires when installing the lights, but looking back I think they might have been routed near the headlight opening.
Just checked a schematic printout from my W201 CD (bought from you folks
) -- says that the fuel gauge and water temp gauge are wired together and have a 0.5mm brown wire as ground. It terminates to W1 (R14) "main ground behind instrument cluster via blower motor resistance group". I never touched the instrument cluster (honest). Could this instrument cluster ground continue on to the chassis ground? Or, does it terminate at the cluster? I have to bring the car in to repair the odometer/tripmeter anyways, so "they" should be able to troubleshoot/repair this "jumpy needle" syndrome, right?
Thanks for any additional insight(s)!