1988 Johnson 70 VRO Tach not working

[cclements716]

Boat has ran great until a few days ago. Tach stopped working. The engine is charging the battery but I have no signal at the tach. When I turn the key on the gauge zeros and has a good ground and positive feed. I have checked on the block and connected the yellow/gray with the gray and still no reading. I have completed the rectifier test with an ohm meter and only shows movement in one direction. Brand new batteries and clean connections. The vro has been disabled (unplugged) and the engine has ram fine without it. Never had any problems with the tachometer until now. Any suggestions?

 

[Joe Reeves]

Re: 1988 Johnson 70 VRO Tach not working

If the rectifier checked out okay and the stator is charging the battery as you state, and the tachometer bottoms out when you turn the key on, the voltage portion of the circuit is as it should be.

That leaves either a broken sensor wire somewhere between the tachometer and the rectifier, or a failed tachometer.

 

[cclements716]

Re: 1988 Johnson 70 VRO Tach not working

When I take a dc reading at the rear of the tach it reads some where around 6.5volts. When I checked charging the voltage did seam high. I think around 18-19 volts.

 

[cclements716]

Re: 1988 Johnson 70 VRO Tach not working

Ended up the tach was bad.