I have a 1988 300E that I recently pulled the instrument panel to check my hall effect sensor as my cruise is working intermittently. I will solder the cruise brain as that is probably the problem. I must confess that I forgot to disconnect the battery cable. I don't know what happened but since I plugged the instrument cluster back in, the oil pressure and the tach are not working. Any ideas or suggestions. I checked all the fuses in fuse box with an ohm meter and they all seem to be fine.

That happened to me before. I took the instrument cluster out to fix something, when I reinstalled it the tach did not work. I double checked my connections and it was unplugged. Double check the connections. I bet they are unplugged.

I have double checked my connections and they are all good. The tach works but is almost like it is lazy. Will not respond to different revs like at high rpms it is only reading about 3000rpms.

Tell me if the cigarette butt trick might work in the dianostic connector? I am not quite clear on how to do it. Do you just take the cap off the diagnostic connector and put something there to apply pressure or do you take apart the whole connection?