I have a 380se, W126 chasis, and am having similar issues with major dash functionality problems. Erratic tach, speedo jumping around at a dead stop, turn signal intermitant functionality, surging cruise control while it kicks in and out, all gauges bouncing around. I am think for this much to be going TU, there has got to be a ground problem.

Just how hard is it to get to that major ground point behind the dash? Are we talking complete dash extraction? Or pull a few screws and viola?

Many similar symptoms

Thanks.