I'm not getting the warning horn test beep. Question about testing and fixing horn.

[Bumblebeeman]

I have a Bumble Bee bass boat I switched motors on last year. I took off a 1991 XR4 150 with the original oil injection still working fine and put on a 1996 200 EFI that had already had the oil injection removed years ago. On first start up with the new motor on I got a constant alarm and found out I had to disconnect the wire sending the there's no oil alarm. A mechanic at a Merc dealer told me which wire to disconnect and I don't remember now what wire it was. The boat I took the 200 EFI off of had one of the wires to the warning horn cut - maybe that's how they fixed the constant alarm on that boat.

I wasn't getting the momentary beep at first key turn on so I started looking into it. I tested the horn and hooked straight to 12 volts, it beeps. The reason it doesn't beep when installed is I discovered the tan wire coming from the engine is bad or I am working with the wrong wire. Is the tan wire coming out of the boat side of the big multi-pin plug the overheat alarm wire or is it a different wire? I did notice that at the ignition its tan with a blue stripe. When I run my own separate wire in place of that tan wire from the engine to the horn and hook it to the tan wire going into the engine and measure voltage between that wire and the purple wire that attaches to the horn I get 0.0 Volts with the ignition off and 11.78 Volts with the ignition on.

Can anyone offer my guidance on if I am experimenting with the right wire and how to fix the warning horn? Another question - If the oil injection is removed and you don't remove the oil warning module, which the person who removed the oil injection years ago did not remove the module and I disconnected a wire the Merc mechanic told me to to fix the constant alarm, and if everything is hooked up correctly, will you get the brief horn beep check when you first turn the key? If you don't how do you know the horn is working?

Thank you

[JOE54]

leave wirring as is from xr4 , tan wire at cannon plug is for gage,tan blue strp from module is one you looking for if oiler is disconnected disconnect it or purple wire from module at junction block leave temp sensor connected with key on jump to grnd horn will sound for overheat but not at key on

[EuropeanAM]

Normally if the oil injection is removed, the OIL WARNING MODULE IS ALSO REMOVED.

That means "no test beep" at keyup (just an overheat warning).

Look for the wiring junction on the STB side of the engine, has tan w/blue stripe wires connected together. With key on, if you ground this junction terminal, the horn should sound a SOLID tone (indicating the horn is functional). The junction would be STB side temp sensor to wiring harness (both tan w/blue stripe).

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