Tach works sometimes, get the rev limit horn sometimes on startup, get the revhorn sometimes while at low rpm and tach comes back. Any easy tests without pulling dash? 1990 GXL.

 

I am pretty sure it's the connector by the trailing coil. 4 wire one I believe. its probably loose, see if thats it.

 

Next time that the tach does not work, rap on the plexiglass cover in front of the combination meter i.e. the rpm, speedo, fuel, oil gauge cluster. If the needle responds to a good rap, then its in the combination meter area. I do have this malfunction on one car. Happens once a month. Rap will work until I find the wanna to fix it. Not worth the effort today.