Hi - The tachometer of my Mercury 1993 ( 51950 miles on it )is at 0 rpm - will not move - once in a blue moon it will start working and than dies down.
What might be the problem - Request a clue from the experts. Thanks
The tachometer gets it’s signal from the ignition coil and is then grounded. So there might be a bad connection at the ignition coil, the electrical connector behind the instrument cluster might have a bad connection at the pins, or there’s a bad ground which is located under the dash.
Tester
The module triggers some Ford tachometers and when the tach fails ignition failure is sometimes the next shoe to drop.
Most likely the VSS (vehicle speed sensor) is failing. This input is required by the computer to determine transmission operation (shift points). Not an expensive item but hard to get at, located about center back of engine block facing fire-wall.