Remote control alarm on non-VRO motors

[johnyrude200]

I have an ’85 25hp remote motor where I’m using a 90’s control box, and it is chirping at me. The manuals say low oil, obviously this motor does not use a VRO. Is this a faulty control box?

I disconnect the overheat sensor at the cylinder head and no more chirping. The chirping gets louder as the motor heats up, yet basically stops after going WOT throttle when it’s pumping like a fire hose.

Using a heat laser, confirmed the motor is not running hot (thermostat at top of cylinder head was 105-115).

[dan-in-tn]

Several possibilities. Could just be a bad horn if the chirping is irregular. Turn key on & off quickly to see if it hangs up – ON. Could be the sending unit in the head. Before you change either of those, change to QL77JC4 Champion spark plugs. Sometimes RF will cause the horn to go off irratically. This can be because the plug wire is close to the sender wire. NGK does not make a "Q" derivative plug so they can’t block the RF. See if any of that helps. Don or Pappy may have another idea.

Dan in TN

[fleetwin]

OK, so you are using a 90s style control box with the "self test" horn. In other words, the horn chirps for a second every time you turn the key on, correct? Dan is soooo right about the plugs, use of the non inductor plugs can drive the warning systems crazy. You mention the engine isn’t overheating but the horn shuts up with the temp sender disconnected. Like Dan says, try to route the send leads as far away from the coils/plugs/wires as possible.
Replacing that sender is a royal pain on that engine. Do you have another control box you could just plug into the engine to try out? I suppose an intermittent/bad positive connection to the horn, or perhaps a weak horn ground might drive it crazy as well. I don’t know how voltage sensitive these horns are, but suppose real low or excessively high battery voltage might drive the horn crazy as well.

[johnyrude200]

It was chirping at a regular interval, and the volume would fade out based on the motor temp. This motor did have a weak impeller which I replaced today and fixed the cooling system (all o-rings were new so no culprit there).

I have dozens of control boxes and the white ones had no chirping on this motor. So first ‘black box’ Ive used and appreciate the heads up. Will reroute/move wires accordingly moving forward as this is one I installed on my test boat so it will see a lot of use moving forward.

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