Mercrusier Tach now doesnt seem to work

[truckermatt]

Hello all.

My tach on my merc 4.3L doesnt display accurately anymore. Last year it worked fine. but now to moves but is way off.... and it consistently "resets" by going from zero to 6000 then back to zero then to engine RPM which is incorrect anyway... The same thing it always did when you first start it up....(last year.)

All that has changed was the dealer winterized it in fall... and in spring i installed a new stereo...

all the other electronics work fine.
Just curious to know if people have heard of this.

 

[Philster]

Re: Mercrusier Tach now doesnt seem to work

Check connections on ALL the gauges.

For the tach to work: You need black (ground), purple (key on power) and gray for the signal. With engine running, test the connections with electrical tester. When revved up, the gray signal wire should read a few volts. Barely any at idle. For tach lighting, you also need the blue wire.

Tachs go bad. But, since electrical work was done, it is possible that the tech gets it's power from another connection point on another gauge which got knocked loose or redone poorly. In other words, it is daisy chained in, and if the connection is bad/loose up the chain, it will lose power.

Or... gamble and replace the tach. The only reason I would not right now is because someone was back there and could have screwed up the connections. Happens too often.

 

[truckermatt]

Re: Mercrusier Tach now doesnt seem to work

i will try testing it when i get to the boat...

FYI: the tach does diplay some RPM reading just not the right one, so i know it is getting power.