Our VDO tach (Beta 43 with 1600 hours) is gone all weird. It rarely shows the actual engine speed, at best sort of hovering in a 200 rpm cyclic. Usually the needle just parks itself in the 1200 rpm range and sits there.
I swapped out the alternator (Iskra 100 amp) to find no improvement so I begin to suspect the tach itself. Can anyone direct me to a troubleshooting source so I can continue my investigation?
Check the continuity of the blue wire with the black tracer between the W terminal of the alternator and the tach. If this wire has grounded on the engine at all, it can cause the issue that you are having. If this wire is good, then the tach is at fault. Stanley
