No Warning Horn at All

[RideNFishCA]

2005 Merc 115ELPT4S four stroke 1B158433 - First time boat owner.

No warning horn, ever. No short beep at start up or otherwise. I removed forward controls (side mount) and made sure purple wire was hot with key on. I grounded tan/blu wire and horn went off. I am worried that previous owner hid something from me and I didn't have the experience to catch it. Last time out couldn't reach full speed and boat has no tack. Seemed to be running fine otherwise.

I found two wires unhooked at harness under cowl but I think those are for an analog trim gauge. I believe this is the Yamaha powerhead years hence the harness adapter from 10 pin to 8.



Can I try to force warning on water temp or oil pressure by grounding wires since I know the horn works at the forward controls?

Thank you in advance.
I have some mechanical experience
Moderators, please let me know if I can improve info for efficiency.

Cheers!

 

[Texasmark]

Failure is a ground so you would be simulating a ground....nothing in the circuit but switched 12v from the ign sw, the horn/dash light, and the ground you are playing with.

 

[RideNFishCA]

Failure is a ground so you would be simulating a ground....nothing in the circuit but switched 12v from the ign sw, the horn/dash light, and the ground you are playing with.

I have the boat in storage so will ground sensors to see if I can get horn. Any idea as to why I don't get the short horn beep turning the key to "On"?

 

[Texasmark]

Yes. If you don't have a modulation module, there is nothing to instigate it. Horn is operated off Key switch from OFF to ON. In the ON position, 12v is fed to one side of the horn....red with purple stripe wire. Other terminal runs down the tan or tan with lt. blue stripe to the outside of the engine connector on the starboard side of the engine....dangling freely as in your picture. I notice that nothing is connected to that wire so you won't be getting any horn blowing from engine problems. Grounding it will blow the horn if everything is operable back to the Helm.