tach problem

[shavedhead]

1999 merc. 50 Boat had no guages, I installed tach, using tach harness from controls,gray to sig,purple to + ground to ground buss bar,tach set on 6p, go to lake and it does not work, l read about checking voltage regulator, so I am looking at reg. and see one of the yellow wires is burnt at bullet connector and wire insulation is melted about 1 1/2 inches on the side of connector away from reg.Can I cut and soldier in a new piece and hope for the best or do I replace reg. Thanks for advice.

 

[Texasmark]

What melted the connection? If it was of an external cause, not related to your yellow wire battery charging/regulating circuit then have at it. If there was no external player then you could have a corroded set of terminals there. That causes resistance and when you push current through a resistance you generate heat and that melted your insulation. Question then is, is this just from corrosion at normal operating currents, or did my rectifier/regulator short out, or did I attempt to charge a discharged battery and maybe overheated the module causing it to fail?

That ought to get you going. If you want more, the manual gives you trouble shooting tips with values of resistance in the circuit to help you find the faulty component. But yes your hookup is ok and yes your tach signal comes from the rectifier module.

 

[shavedhead]

I just bought the boat so cannot answer with any knowledge as to what happened, I was looking at things and found the wire like that, I guess I can just repair it and keep an eye on it to see what happens

 

[Texasmark]

Right answer. Before you go out again, get on muffs and a water hose and run the engine for 15 minutes or so. Monitor the tach and battery voltage (for charging) and feel the module and yellow wires. If battery is nearly fully charged, the module should stay relatively cool. If shorted out, it will get hot rather quickly and the tach probably wown't work and the battery won't be charging.