Tach trouble shooting

[rioraton]

I have a 92 Nissan 90 NS 90A 3B7-1 Outboard My tach stopped working or should I say worked intermittently. Replaced with New/used one. Still does not work. So, I think I have a wire issue. I do not know how to go about trouble shooting the issue. I have the following wires: Blue & Black Wires, Yellow & White wires, and Green and Red wires coming out of tach. What are each wire for, where do they go and How do I test them with multimeter. ANY info would be helpfull

 

[dingbat]

Don’t know about your Nissan, but an inoperable or flaky tachometer are classic symptoms of a dead or dying voltage regulator.

 

[legalfee]

Yes I'd suspect a bad regulator / rectifier.

 

[briangcc]

In that last pic, where all the wires kinda come together, there's (2) blues and a red joined in what appears to be some sort of shrinkwrapped barrel connector. It looks like a very wonky solder joint is there. Same goes for the barrel connector behind it.

IF it were me, I'd start by getting those connections solid.

From there, there's probably (2) wires feeding a backlight on the tach. You should be able to figure those out with a meter - my hunch given the wires going to them, is its the two barrel connectors. Just a WAG but based on what I can see, seems appropriate.

From there, another WAG, the next two pin connector might be a warning or choke light?

Kinda leaves the 3 going into the tach itself which is probably power, ground and tach signal.


Total WAG so may be completely off in left field....