Engine Synchronizer Gauge

[Cork the Whine]

Hi, We own a 97' 355 AC with twin Crusader 454 Xli's. My question regards the synchronizer gauge at the helm. Where does the input to drive the gauge come from? The Gauge is always pointing in one direction or the other, regardless of engine speed. Does the signal come from the tachs or elsewhere? Any help would be appreciated, I believe the tach's to be accurate based on what I hear from the engines. Or does the signal come from the engines? This is just more annoying than anything else.

Thanks in advance!

[bud37]

Try a search of the forum, there has been a few threads about these gages, issues, fixes, with some part numbers etc.

What kind of gage do you have, the original in the dash ?....if so have a look under the dash and follow the wires back from the gage and see if they go to a black box looking module, it won't be far if that is the style you have.

[Viper]

For that vintage, the sync gauge is likely getting signals from the back of the tachs. Unless it's a faulty gauge, the reading is only as good as the signal from the tachs. In most cases, it's actually inaccurate tachs that are the source of errant readings. To ensure the tachs are accurate, you should take a reading at the engines and compare that with what the gauges say, then go from there as there are a couple of things you can try to remedy inaccurate tachs if that turns out to be the cause.

[tomschauer]

The sync gauge "piggy backs" the the tach signals from the engines. It does not actually get signals from the tachs.
Under your helm is a small black plastic box that feeds feed the synch gauge. Find it and follow the leads to the back of the tachs and clean and tighten the connections. If it still doesn't work, replace the box. I replaced mine about two years ago, maybe I can fine where I bought it if needed.

[g36]

I believe its a beede guage and you will find a sticker on the black box that has the info on it. I replaced my sync guage with another option i found on ebay. I may still have my old stuff I took out.

[Viper]

Forgot about the black box, it's certainly a consideration for sure. Knowing the brand of the gauges would help.

[Cork the Whine]

Guys, Thank you for the direction.

[mjk1040]

My tachs hardly ever match, if I tap them they fall in sync.

[Njoyable]

Another year, same problems
Can anyone advise what the “black box” is called? I’ve looked at mine but find zero lettering on it and people just look at me funnier than usual when I ask about it. Meanwhile, my synchronizer does exactly what the OP’s is/was doing.

[tomschauer]

https://fariabeede.com/site_manuals/bee ... 547227.pdf

This may help.