4.3 LX Warning Horn Problem

[humpbackshooter]

The warning horn on my 4.3 LX continues to sound / buzz all the time. I have taken it to a boat shop and they said they can't find the problem. They checked out the engine and found no problem with it. So they just cut the wire to the horn. Told me to watch my oil and temp gauges. That I should be fine. I did that and made the it to the end of the weeks vac. and all was happy.....BUT I'm not going to let it sit.....I need to find the answer to the problem.
1. I know that the oil pressure has to come up to stop the horn......oil pressure gauge (on the dash) shows pressure and the engine sounds good-no knocking or bad sounds.
2. There is oil in the tank for the lower unit. This should not cause a problem unless it gets low....which means I have other problems.
3. Engine temp is fine. That means that the water pump is moving water and not over heating. ( Dash temp gauge shows in the normal)

I'm thinking there is a short in the wire.......I think this a TAN / Blue stripe wire that goes to all the temp sensors and oil pressure sending unit and the oil tank for the lower unit. This horn works off of the ground of the motor. IF the float in the tank drops.....this causes a grounding from the switch closing and signals for the warning horn to play. Same for the oil pressure sending unit ONLY it must sense pressure and OPEN to Stop the horn. IF its the temp probes they should be open till the temp reaches their high limit and thus CLOSE.....again causing a grounding and then there is this irritating buzz of a noise. This problem started right after I took and washed the motor and motor compartment out with the water hose.

Is there any other place that may come into play? I am thinking that these are the only safety connections.

Phil

 

[humpbackshooter]

No Title

Serial # on block..

1996
Maxum 1900 SR

 

[Bondo]

I'm thinking there is a short in the wire.......I think this a TAN / Blue stripe wire that goes to all the temp sensors and oil pressure sending unit and the oil tank for the lower unit. This horn works off of the ground of the motor. IF the float in the tank drops.....this causes a grounding from the switch closing and signals for the warning horn to play. Same for the oil pressure sending unit ONLY it must sense pressure and OPEN to Stop the horn. IF its the temp probes they should be open till the temp reaches their high limit and thus CLOSE.....again causing a grounding and then there is this irritating buzz of a noise. This problem started right after I took and washed the motor and motor compartment out with the water hose.

Ayuh,..... You've got it,...... Disconnect each one, 'n track down yer problem,.....

I've heard the oil bottles get crud in the bottom of 'em, causin' such issues,....
Or the other switches could be bad,...

It's the water temp switch, not the gauge sender, 'n the oil pressure switch, not the gauge sender,.....
2 different animals,... usually located very near each other,.....

 

[Fun Times]

Hi there, bear in mind that just because everything seems to be working properly on the dash gauges doesn't necessarily mean one of the discrete switches that work the warning system hasn't failed internally. The gauges and warning system use separate sensors and switches.

One test you can do is start removing the Tan/blue wire one at a time to see if the horn stops sounding...On the drive oil reservoir, be sure to disconnect both wires going to it.

If the horn continues to sound with all three disconnected, then like you say the Tan/Blue wire may have a short someplace between the engine and helm/horn. Or the horn itself is defective. Using a multimeter, try Ohms checking the wiring and switches....Also try removing the main wiring harness cannon plug at the engine for inspection.< Wiggling it and wires may help as well.

http://www.mercruiserparts.com/Show_...CAL+COMPONENTS
http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=809969+96

Also find yourself a new service shop.:facepalm: Good luck.

 

[jccarter]

Not trying to jack your thread but same is happening to me today salmon fishing. Where did the shop cut your wire at?

 

[achris]

Not trying to jack your thread but same is happening to me today salmon fishing. Where did the shop cut your wire at?

DO NOT cut any wires. Find the problem. Just fixed a friends' boat that had corroded out the back of the oil pressure switch. While running about 10 miles out to sea it pumped all the engine oil into the bilge. Had it not been for the alarm, we'd be fitting a new engine right now. The switch was $75....

Chris.....
(EDIT: Or you could just read THIS thread. Same thing)

 

[humpbackshooter]

Thanks bondo & funtimes. I may have found the problem while I was getting some tools out of the boat. I notice that the two wires that come out of the bottom of the reservoir for the lower unit fluid was layin on the side of the engine. Broken right where they come out the bottom of the tank. If they were shorted together.....then that's where my problem lies. I have not gotten to ck it yet. Will do so hopefully tomorrow.

JC......they / I cut it at the horn itself. It's just under the dash, under the steering wheel.

Thank,
Hump / Phil.

What is the part # for this tank or they gerneartic .

 

[humpbackshooter]

JC.........leave your self some room to wire nut it back once you find the problem.

Hump

 

[humpbackshooter]

JC........ Take Chris' advice......this happen to BIL. He cut the wire and ran it. No oil in the reservoir. It was stained. Looked full. Didn't take the cap off and ck. engine did what it was suppose to do.......cut back to a slower / low idle. But would not run when given more throttle. End result.....rebuild head. It is a outboard 90 mrec.

Hump

 

[humpbackshooter]

Did I read some where that the temp on the two exhaust were different? That one will be warmer than the other?

Hump

 

[Fun Times]

What is the part # for this tank or they gerneartic .

8M0075708 http://www.mercruiserparts.com/Show_...LE+AND+BRACKET

If the tan wire was shorted to the engine then that would sound the warning horn.

jccarter, Keep looking for the problem vs cutting the wire, you'll eventually find out why.

 

[achris]

As an EMERGENCY ONLY, you don't need to cut anything. The buzzer is connected to the instrument harness with just a bullet connector. IF YOU MUST, just pull the connector out, that will stop the alarm sound... (and not tell you when something is wrong!)

Read far too many threads for people thinking the alarm was faulty, disconnecting it, only to find the alarm was telling them there is a problem. And it costing a lot more than just attending the original problem in the first place. If your temperature gauge was showing that your engine was running hot, would you just disconnect it because you didn't want to see that gauge reading so high? I think not, treat the alarm the same way!

Chris.......

 

[humpbackshooter]

Thanks, achris......I'll have to see if the local shop has one or have to get it off the e-net.

hump.

 

[jccarter]

Not cutting anything! Just watching this thread, all good advise, and helpful. If I cant figure my problem I will start my own thread. Thanks

 

[humpbackshooter]

Took the boat out today. Ran great. Had a little miss at first, but it cleared out by time we put it back on the trailer. I think it was just the old gas that was in the tank. I put some new in prior to the trip. So I think once I got that new gas through the carb, it started running fine. Oil pressure at 40 psi on the dash gauge. Temp gauge showed 130f. No warning horn noise at anytime except for when I fired her up. Lots of thanks to all for y'alls in-sight
Hump.