Constant horn

dockwalker · Dec 1, 2009

1990 Evinrude 150Hp.Had submersion problem,cleaned out lower unit.Warning horn sounds continuously,starts with key turn(engine not running),disconnected temp head sensors,still sounding.Engine runs, pumps water(not overheating) Does horn go bad?Any way to check?

kenmyfam · Dec 1, 2009

Re: Constant horn

Submerged in salt water ???
Give us some history on the submerging and the actions taken. Include time as a factor as well.

dockwalker · Dec 2, 2009

Re: Constant horn

Submersion happened last spring insandy water,(only halfway on engine).Replaced water pump,impeller, thermostats,pop-offs.Cleaned waterways.New fuel tank,new filter.Drained carbs.Checked oil and fuel lines (filter too)from VRO.Have detached brown sensor wires from head ,still sounds.Any way to test actual horn or circuit? Could surge limiter cause problem?When I blow on it it goes both ways.Had horn issues previously but never stayed on constantly

mikesea · Dec 2, 2009

Re: Constant horn

does eng run OK,any other electrican problems,what kind of controls do you have,if a remote box,your horn could be grounding in the box,or,you may have a problem with your harness.check the connections at the big red plug,if water got to the wires you may have a grounding whithin the plug or harness,tell us exactly what you did after the sinking

emdsapmgr · Dec 5, 2009

Re: Constant horn

One other thing to check on that engine. You can also get a constant horn from a defective vacuum switch in the fuel system. When the vacuum reaches 7 lbs, it will set a constant horn. Yes, horns do go bad.

jay_merrill · Dec 5, 2009

Re: Constant horn

Not sure about your motor, but the hot horns on a lot of OMC motors sound when the circuit is closed to ground - that's what the thermal switch does. If your horn is getting 12VDC and is grounding somewhere, it would probably do what you are describing.

???

dockwalker · Dec 9, 2009

Re: Constant horn

Like to thank everyone for the help.Found constant horn problem.Short in oil tank.Banged on it and it stopped.Since tank was submerged(Replaced oil and cleaned previously), any ideas on cleaning contacts under the rubber cover? Tried prying up,but was afraid might tear cover.Mighty expensive to replace whole unit($100+)I guess I could disconnect, but reluctant to do so.

dockwalker · Dec 10, 2009

Re: Constant horn

Update!! Basically destroyed sending unit in oil tank.Has circuit board in it,but unsure of purpose.Can anyone explain the operation.Looks and tests like unneededPlease explain float system with metal float?

seahorse5 · Dec 11, 2009

Re: Constant horn

If you don't want to spend for the expensive tank pickup assembly, just disconnect the wires from it at the motor harness.

Watch the oil level visually as the electronics in the tank pickup were only there to alert the operator that there was only about a quart of oil remaining.

dockwalker · Dec 20, 2009

Re: Constant horn

Would like to thank everyone who helped here.Found out that circuit board has sensor that lowers engine RPM if oil level drops too low.Low oil sensor still works so will just keep eye on oil level and shut down if horn sounds.Hope this helps otheres.Have a Merry Christmas!

seahorse5 · Dec 21, 2009

Re: Constant horn

dockwalker said:
.Found out that circuit board has sensor that lowers engine RPM if oil level drops too low.!

Sorry, that is not correct.

ONLY the temp senders slow the motor down when activated. If any other alarm slows the motor, then the blocking diode inside the engine wiring harness is shorted and not working correctly.

The LOW OIL alarm system does not affect the motor in any way, it is only an indicator that there is about a quart left in the tank

Constant horn

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