Connecting A Horn Relay


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Hi, Thanks for the detailed pic for the wiring..

Can you also help me to know the wiring of 3 connector relay..
4 pin is always better.

In 3 pin, terminals would be H, B and S. (Horn, Battery and Switch). Connect Battery + to B via fuse, horn to H and S to horn switch (-ve in most cars).
 
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Bro I have a small problem from where will i get a +12v Wire to connect to a 4 port relay?
Or should a just use the +12v wire of stock horn that is fused to 15A to connect to ports 30 & 85 in above image of a relay ?[frustration][frustration][frustration]
 
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Bro I have a small problem from where will i get a +12v Wire to connect to a 4 port relay?
Sorry for the late reply,Missed this post. Get it directly from the battery + and fix a fuse in that wire close to the battery.[:)]
 
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Actually you don't have to get current to point 30 from the battery you can use the existing+ wire that is originally used for the existing horn arrangement. Most mechanics take it from the battery because they don't know any better and in some cases it can cause a problem as well.
 
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4 pin is always better.

In 3 pin, terminals would be H, B and S. (Horn, Battery and Switch). Connect Battery + to B via fuse, horn to H and S to horn switch (-ve in most cars).
I have one question why 4 pin relay is better than 3 pin relay. I recently installed Minda 3 pin relay in my car and its working well.
 
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Actually you don't have to get current to point 30 from the battery you can use the existing+ wire that is originally used for the existing horn arrangement. Most mechanics take it from the battery because they don't know any better and in some cases it can cause a problem as well.
In this case there is no need of a relay, you can directly use the OE harness to power the horns.

OE harness and horn switches are designed for specific power rating and in most of the after market horn the power rating is on the higher side, which the OE harness couldn't handle (we will end up with melted wires) This is why the OE harness is used as a trigger signal to relay and +ve is directly taken from the battery with a higher gauge wire.
 
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The relay is put not to enhance the + supply. It is there as the horn button gives the earth supply and is generally not enough to handle 2 horns. By putting a relay you invert the switching from negative to positive and the earth is supplied directly. So if you were to join the original + supply to pins 86 and 30 and the horn button to 85 the pin 87 to the horns you would have a perfectly good set up. It is ignorant mechanics who feel that a direct wire from the battery is required. The numbers on the relays arr according to the DIN specification and while interchanging 85 with 86 and 87 with 30 will still work they are meant to be wired correctly to make fault finding more straightforward. Unfortunately in our country training mechanics is done in a very ad hoc way.
 
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The relay is put not to enhance the + supply. It is there as the horn button gives the earth supply and is generally not enough to handle 2 horns.
Does all cars supply -ve through horn switch?
I'm speaking about the one shown below.
Simple Relay Wiring Diagram (JPEG).jpg
 
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I would say that in all the older cars it would probably be-ve switched a
s they would need to take only one wire. In the newer cars with canbus systems I am not sure. If the car has a horn relay as original it would probably supply positive switched to the horns.
 
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I would say that in all the older cars it would probably be-ve switched .
while installing horn and relay I saw two wires connected to the oem horns. To check the polarity I touched both wires with the body one by one to get spark, in this method I end up by blown fuse:stupid:. replaced by spare one available. So what you say about nano, is it with old wiring, or am i getting wrong.
 
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mostly horn wiring works on -ve supply ie when you press th horn button it earths the wire & -ve voltage comes to the horn completing the circuit. +ve is always at other point this arrangement is because if 12v +ve is at horn contact it will make spark due to +ve connection & relay is necessary for high amperes & current. in OE horn wiring wires are thin & there is resistance in wires this drops the current when it reaches the horns thus horns does'nt sound that good as it should.
that's why giving a direct wire from battery gives it full current (but wire should be of at least 6mm or 8mm),thicker the wire low will be resistance.
 
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I have bosch symphony horn and roots windtone 90 in my cars.
Using them for about a year without any relay without any problem

Is a relay really required for horns ?
 
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