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Hi guys,

 

i am going mad over my horn wiring as it does not work. Here is what I have:

 

5 pin relay:

pin 30 to battery ( fused at 10amp)

ping 87 is power to horn positive . Horn is grounded to the chassis on the other pin so one positive from relay and one from chassis

Pin 86 is connected to horn switch . Horn switch then has a ground to streering wheel column.

pin 85 is ground

 

this doesnot work when i press the button or even when i connect 86 and ground together.

 

if however i give positive to 86 from the starter key wiring , it beeps!!

 

i thought i need ground to 86 but i need positive.

 

anyone that can help please

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car wiring generaly switches to earth.  Your horn button switches to earth.  The other end of the relay coil obviously has to be 12v+.

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3 minutes ago, GTSBoy said:

car wiring generaly switches to earth.  Your horn button switches to earth.  The other end of the relay coil obviously has to be 12v+.

Not sure i understood. The button is getting power from leg 86 of the relay and groun from chassis. 

 

What do you mean car wiring generally switches to earth?

 

any suggestion on what i am doing wrong?

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The two haves of the relay are completely separate.  The power to run the relay's coil comes form the car's original circuit.  The power that eventually runs the horn (on the switched side) is completely separate.  The drawing for how to hook it up is usually printed on the side of the relay.

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I have followed it and it is not working hence the post.

 

my understanding is when i press the button pin 86 and 85 are energised so 87 and 30 are linked thus power goes from battery ( 30) to 87 the horn .

 

 

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12V+ -> relay coil -> horn switch -> earth.

That's what you have to get right.  The other side (the output of the relay) is easy.

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12 hours ago, GTSBoy said:

12V+ -> relay coil -> horn switch -> earth.

That's what you have to get right.  The other side (the output of the relay) is easy.

can you please explain it in wire to pin term.

I explained above on how I have connected it and again below:

 

power from battery to pin 30.

ground - pin 85

power to horn - ping 87

wire to switch / horn button - pin 86 . this is then grounded on horn side 

 

sort of like below

 

https://www.google.com/search?biw=1920&bih=1009&tbm=isch&sa=1&ei=D4JYXLbQNcHkgwefjJWYAg&q=relay+horn&oq=relay+horn&gs_l=img.3.3.0i67j0l5j0i7i30l3j0i8i30.24132.24132..24379...0.0..0.48.48.1......1....1..gws-wiz-img.BEvgJH0xOJU#imgrc=mccxtHvKA7bRDM:

when I push the horn, 86 and 85 is connected so power should go through from pin 30 to 87 which doesn't happen.

86 is not hoocked up to any other power source so not sure when I press the button, whether 86 gets power from relay to connect to 85 or ..

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Every time I do this (every five years or so) I have to figure it out again.

pin 30 power from battery (correct)

pin 85 also requires power (can take from pin 30 or the original power source)

pin 87 goes to horns (correct)

pin 86 goes to horn button

This applies to the usual set up where the horn works by earthing through the horn button i.e. the horn button is not supplying power it is completing the circuit by earthing.

 

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So does 85 need power, it is ground?

 

86 has no power , simply a wire to button which also has a ground connection

 

if i touch power/12 to 86. It does beep

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1 hour ago, drifter17a said:

So does 85 need power, it is ground?

 

86 has no power , simply a wire to button which also has a ground connection

 

if i touch power/12 to 86. It does beep

Sounds like you are in a bit deep here man. Baby steps, walk before you run etc. 

relays aare sosimple. They have how they work on the side of them ......

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6 hours ago, drifter17a said:

So does 85 need power, it is ground?

 

86 has no power , simply a wire to button which also has a ground connection

 

if i touch power/12 to 86. It does beep

Just follow my instructions. If you think you know better why ask?

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7 hours ago, KiwiRS4T said:

Just follow my instructions. If you think you know better why ask?

will swap 85 and 86 and post back

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NO!  It does not fu(king matter whether you have the switched side going in or out of either 85 and 86.  They are BOTH just terminals that are connected together inside the relay when you power the coil.

What matters is that you put battery power into one of them, and the connect the horn button (and therefore the EARTH on the other side of the button) to the other switched terminal.  The earth is provided by the horn button being pushed, closing its switch and connecting to earth.  The power flows to that earth through the relay from the other side of the relay's switched terminals.

I have just rephrased what I have posted before, and what Kiwi posted.  Same same.

Not rocket surgery.

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Lol, don’t fume:)

Trying to understand this.

would you get a direct battery feed to either leg 85 or 86?

I think the problem as i suspected and you pointed out is neighter 85 or 86 have power to energise the relay and I have been confused by looking at relay wiring instructions.

 

if I get an accessory light to 86 , 86 it will not draw power from that accesorry to power the horn, it is simply used to energised the relay so i don’t need to fuse it , do it?

 

power is supplied from pin 30 to pin 87 which goes to horn

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Actually, I dun f**ked up.  But only because I don't care which terminal is which number.  I mixed up the switched side and the coil side.  Look at the below image....

image.png.e7c1dd6bac03ab98df55629e1982b214.png

Power to run the load (the horn) actually goes in through T30. T87 is the output to the horn.

T85

Now, you could do either of the following (but not both).

1) You could swap the connections I described in the underlined text to be the other way around if you wanted to.  It would still work.  Those terminals just get joined together when the relay's coil is powered.

or

2) You could put the same power supply onto both T30 and T86 (using a wire that connects them both outside the relay AND to the power source of choice).  Then the horn button (and its earth) get connected to T85.

 

It is usually important to put the activation power onto the right terminal (that would be 12V onto T86) because they often have a diode in them to stop back voltage spikes when the relay is opened (ie, when you turn it off).

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Give a man a fire he is warm for a while. Set him on fire he is warm for the rest of his life. 

 

 

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Just revisiting my decision, i have directly plugged 85 and 30 to battery meaning horn works regardless of ignition status.

 

It is not the best to leave it direct to battery so want to rewire 85 to a positive ignition that is switched with ignition, what would you use?

 

i am thinking to use fuel pump or some fuse that comes on with ignition.

 

is it a bad idea to do that?

 

there will be no draw from pin 85 or minimal , right? Should I fuse it to 2 amp or so as it is only energising the relay so power from battery is sent to horn directly 

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