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New 12v Horn Won't Sound
I replaced a drop in horn in my forward anchor box with a new 12v trumpet. The drop in functioned fine; however, wasn't loud enough to even hear in the cockpit. The new horn worked on initial test with battery voltage only. Three weeks later on the water it's dead on battery and while engine running. Back on land a test netted what sounds like a pop of the diaphragm and when hitting with my hand it will sound. I figured bad diaphragm and had the horn warrantied. Now the replacement does the same thing! Battery volts at the leads where the horn connects is 12.7v. Both horns work when jumping directly to a battery. Emailed manufacturer. What am I missing?
Thanks for any help you can lend Keith |
Probably needs thicker guage wire run to it. Run a test length of 10 guage wire from the switch to the horn.
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Originally Posted by Griff
(Post 4642278)
Probably needs thicker guage wire run to it. Run a test length of 10 guage wire from the switch to the horn.
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Originally Posted by Tractionless
(Post 4642436)
Is the thicker gauge wire carrying more amps? I'm only dropping .15v from at battery (test) voltage 25' forward and through the switch. |
Originally Posted by Ryan00TJ
(Post 4642457)
Thicker wire is capable of carrying more amps. Current/amps will be determined by your load ie horn in this circuit. I'm assuming your voltage measurement is at the leads with no horn hooked up? Connect your horn and turn on. Meter again and see what your voltage is under load.
Keith |
Too much of a voltage drop. Test run a thicker wire
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Originally Posted by Tractionless
(Post 4643169)
should the voltage stay constant?
Keith just like everything else.imagine if your ignition system/fuel system and vehicle electronics went to 5 volts under use. Like your horn, nothing would work. |
Gotcha,
10ga wire in hand, if that fixes it I have no idea how I'm getting it from the helm to the anchor box in a permanent install. Cross that bridge when I get to it I guess. I did run the boat this weekend and noticed a HUGE drop on the helm voltmeter when attempting to sound the horn with engine power. The gauge dove from 14v to 12v!! Seems extreme to sound a horn haha. Keith |
How many amps does the horn draw? Seems like you have a short somewhere.
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Originally Posted by underpsi68
(Post 4643772)
How many amps does the horn draw? Seems like you have a short somewhere.
Keith |
At 3.5 amps if the helm is going from 14v to 12v you have a short somewhere.
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Originally Posted by underpsi68
(Post 4643783)
At 3.5 amps if the helm is going from 14v to 12v you have a short somewhere.
Can the switch be bad and causing that drop? Keith |
I agree, is the switch good, do you have power to the switch. a 12 Volt automotive horn has little to no draw, I doubt it the wire gauge, but worth a try I guess.
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Tested the Contura 2 switch and it's good. There's only 2 wires going to it, power in and power out to the horn. I unplugged them from the switch and touched together. I get the same result from the horn. Next up is running a horn power wire from the helm to the horn and touching to the helm supply power to it and seeing what it nets. If it doesn't sound, it's gotta be the ground which will be tons of fun. Keith |
Sounds like the new horn has a greater current draw, you should use a relay and pull power from your amp wiring or similar, even if you get it to work with bigger wiring the switch probably wont last
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The draw is 3.5 Amps as posted above. The switch is rated at 20 amps. Where are power to switches typically pulled from in the helm? That would require modifying source to the battery? Keith |
Typically the helm power comes directly from a distribution block that is fed from the batteries. On many boats the gauge of that wire is barely enough to get the job done with the stock components blowers etc.. If you have a one wire alternator then you will not see the designed voltage at the dash. Marine alternators have remote voltage sensing in order to compensate for the distance. Assuming it is as designed you should first try supplying a temporary new ground direct from the battery or ground block, then try running power from the battery or distribution panel, a "power probe" is a great tool to have for problems like yours.
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Originally Posted by Wobble
(Post 4644955)
Typically the helm power comes directly from a distribution block that is fed from the batteries. On many boats the gauge of that wire is barely enough to get the job done with the stock components blowers etc.. If you have a one wire alternator then you will not see the designed voltage at the dash. Marine alternators have remote voltage sensing in order to compensate for the distance. Assuming it is as designed you should first try supplying a temporary new ground direct from the battery or ground block, then try running power from the battery or distribution panel, a "power probe" is a great tool to have for problems like yours.
It’s not a 1 wire alt. its a circa 1996 Mando on 7.4l LX MPI’s. Also even at engine running volts (13.8-14 typically), still no sound and the battery gauge crashes 2v upon sounding the horn. A power probe as in test light or are speaking of something else? Thanks for the above info. Off to find the power & distribution blocks. I’m guessing somewhere near the breaker panel. |
Originally Posted by Tractionless
(Post 4644959)
It’s not a 1 wire alt. its a circa 1996 Mando on 7.4l LX MPI’s. Also even at engine running volts (13.8-14 typically), still no sound and the battery gauge crashes 2v upon sounding the horn. A power probe as in test light or are speaking of something else? Thanks for the above info. Off to find the power & distribution blocks. I’m guessing somewhere near the breaker panel. |
Picked up a Power Probe after some research. In the meantime I ran the 10ga power wire from helm to horn today which did not fix the issue.
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