Tachometer Not Working

[Blue Cruiser]

We have twin Volvo Penta 5 liter Inboard/Outboards. Initially this summer both tachs did not work at all, no needle movement. After disconnecting all wires on each tach, cleaning the electrical contact and reconnecting all wires; the starboard tach works, but the port tach is still not working. Any ideas to remedy the problem would be appreciated. We have just over a 1000 hours on each engine.

 

[Sandy]

Does the port tach move at all or even light up?

Many tachs have a tiny rotary pulse, pole or cylinder setting choice switch on the back and the manufactures usually recommend noting the original setting to go back to, then rotating the switch back and forth a few times to clean internal contacts as a 1st step if tach is not working correctly.

If that doesn't work, or your tach doesn't have the switch, I would try swapping connections between the 2 tachs to determine whether the tach or wiring is at fault.