2003 50 hp Johnson System Check warning horn works intermittently

[lakelover]

When I turn my key the System Check (BRP #177107) runs through a self test where the lights all come on and then shut off one by one. The warning horn is supposed to make a short beep at the beginning of the test, but only works intermittently. Sometimes it does & sometimes it just makes two very short, barely audible "chirps" that I can only hear ifmy head is right next to the horn. The System Check/tach is only on its third year, I installed them new in 2011 and I believe that other than the horn problem, it is operating correctly. Tachometer always works, it just started doing this last fall, then the boat was stored over the winter.

I unplugged all the harness connections on the back of the tach and in the motor, and put a touch of dielectric grease in the connections and on the boot seals, and plugged everything back in, no help. What would be causing this problem? Could the horn be bad?

 

[lakelover]

^^^

 

[daselbee]

Tach is bad, in my opinion. This is the tach, right? Or is it the gauge? Either way,
if you want to get deep into it, you can hook up a test light to the tan/blue wire coming from the tach to the horn.
Watch the light, run the key ON sequence, and see if the light behaves as you think it should.

If light "blinks" just like the horn should "chirp", then the horn is bad.

Or, start engine, ground one of the tan temp wires on the head, and see if the horn blares for ten seconds, and make sure the "HOT" light is lit on the tach. If it does, then horn is good, and something is wrong with the tach itself.
Engine must be running.

 

[lakelover]

Thanks, I'll look into it. It is the tach model, the tach reads RPM's OK. Might be a while before I can get to it, the boat is at the lake and I'm not! Not sure whether it's a bad horn or not, you'd think it would either work or not work instead of working sometimes. But I'll check out your suggestions.

 

[lakelover]

A post-season update...The warning horn and all worked OK mostly all summer. I noticed that the few times it did not sound were during very high humidity. Otherwise, motor and System Check worked fine. So still a mystery.