steve8274
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| posted on 21/7/12 at 08:42 PM |
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horn wiring
hello all
i recently acquired a new steering wheel to replace the original ford one.
it has the small horn push in centre of wheel
i have purchased a boss for it
when i have wired it up, the horn works fine until i place it into the boss. when it is placed in boss, and pressed, horn doesnt operate and the
ignition lights dim/flicker
the horn push only has 2 wires, 1 positive and 1 earth.
on the side of horn casing, there is a bit of spring sticking out(supposed to be there) which comes into contact with boss
any ideas what i am doing wrong or how to rectify
thanks
steve
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pekwah1
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| posted on 21/7/12 at 09:26 PM |
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wouldn't the two connections be the same, i.e. two earths as essentially the horn button is just a switch.
So the horn itself would have a constant live feed and then by pressing the horn button you are closing the switch and sending the earth to the
horn?
Doesn't really help you too much i know......!
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stevegough
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| posted on 21/7/12 at 09:27 PM |
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Horn is switched earth - that is, the power from the +ve side of the battery is fed to the item, and you complete the circuit by earthing it at the
switch. You are probably getting confused by feeding +ve in from both ends? I think? Erm - now I'm confused! 
Luego Locost C20XE.
Build start: October 6th 2008.
IVA passed Jan 28th 2011.
First drive Feb 10th 2011.
First show: Stoneleigh 1st/2nd May 2011.
'Used up' first engine may 3rd 2011!
Back on the road with 2nd engine may 24th
First PASA mad drive 26/7/11
Sold to Mike in Methyr Tydvil 19/03/14
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craig1410
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| posted on 21/7/12 at 09:43 PM |
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I would suggest using a relay for the horn circuit as it can be quite high current (around 10A) and that might be too much for your horn switch
depending on how it is designed to be used. If you use a relay, here is a suggested setup:
12V---|Fuse|------------------|Relay Contacts|---------|Horn|-----------------Earth (Mounting bolt)
Take feed from above|----|Relay Coil|----------------|Horn Switch|-------Earth (Steering column or other local earth)
If you do it this way you minimise cable runs as the horn can get an earth from its mounting bolt/screw and only needs a single wire from the relay
output. The horn switch can also find an earth locally so only needs a wire to the relay coil. The relay gets its 12V feed normally from the permanent
feed via a 10A or 15A fuse. Again you only need a single wire to feed both the contacts and coil.
The above scheme is very efficient in terms of wiring and I think is the most common in production cars.
HTH,
Craig.
[Edited on 21/7/2012 by craig1410]
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steve8274
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| posted on 21/7/12 at 09:44 PM |
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@pekwah i have checked the wires. one is positive and other negative
@stevegough on the rear of the horn push, there are 2 spade connectors. i have it wired as 1 to positive and 1 to earth.
when i removed the old wheel, at the back of the wheel was a disc with 2 metal rings on that contacted 2 pins on column. this has 2 wires
connected.
i removed this from old wheel and attached to new boss and plugged in new horn push to existing wires.
therefore, i havent wired anything differently than old one.
thought it would have been simple plug and play!! i hate wiring!!!! why does it mock me?
steve
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steve8274
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| posted on 21/7/12 at 09:50 PM |
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hello craig
thanks for the advice
i was hoping to just get it working with existing wires as access behind the dash to add relay etc is very difficult. something i didnt think off when
putting dash in
i will see if i can get it sorted without new relay first
thanks
steve
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craig1410
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| posted on 21/7/12 at 09:52 PM |
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Try swapping the spade connectors around. It sounds like you are shorting it out (light flickering). It might be that one of the spades is connected
to the earth provided by the steering column itself.
Be careful, make sure you have fuses in all feeds to limit any damage.
Cheers,
Craig.
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stevegough
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| posted on 21/7/12 at 09:56 PM |
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quote:
Originally posted by craig1410
Try swapping the spade connectors around. It sounds like you are shorting it out (light flickering). It might be that one of the spades is connected
to the earth provided by the steering column itself.
Be careful, make sure you have fuses in all feeds to limit any damage.
Cheers,
Craig.
Yes, that is a better way of putting what I was trying to say. Thanks, Craig.
(BTW, I have my horn wired up without a relay with no problems).
Luego Locost C20XE.
Build start: October 6th 2008.
IVA passed Jan 28th 2011.
First drive Feb 10th 2011.
First show: Stoneleigh 1st/2nd May 2011.
'Used up' first engine may 3rd 2011!
Back on the road with 2nd engine may 24th
First PASA mad drive 26/7/11
Sold to Mike in Methyr Tydvil 19/03/14
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steve8274
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| posted on 21/7/12 at 10:01 PM |
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think i have tried that but will try again to be sure.
can you confirm that 1 wire should be positive and 1 negative. thats what i have anyway
steve
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craig1410
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| posted on 21/7/12 at 10:13 PM |
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quote:
Originally posted by steve8274
think i have tried that but will try again to be sure.
can you confirm that 1 wire should be positive and 1 negative. thats what i have anyway
steve
Well....I wouldn't put it quite like that as that would suggest that one is 12V and one is Earth which, if you switch them, would be a short
circuit. However, it may give the appearance of being 12V and 0V because the 0V will be earth and the 12V will probably come via the horn and since
there is no significant current flowing, the horn will not drop the voltage at all.
However, it is also possible that the one you describe as "positive" actually DOES come directly from the battery and the one you describe
as "negative" might go via the horn to earth.
If your original steering wheel was a simple, isolated switch then it wouldn't matter but the new wheel might only be compatible with switched
earth horns and you might have a switched 12V setup instead. It's easy to figure out what you have. If you disconnect all wires from the horn
(use tape to isolate them to avoid any shorts to chassis/engine) and then use a meter to check your "positive" wire, see if it is still
positive. If it is then that must be coming from the battery and you must have a switched feed setup not a switched earth. Another clue would be if
the horn uses a local earth or if it has two wires which both go back into the loom.
Let us know what you find.
C.
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steve8274
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| posted on 21/7/12 at 10:28 PM |
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thanks craig
i have checked the wires previously.
the horn only works when ignition on.
when i checked the wires, one is 12volts and other shows as 0 volts(what i was calling negative)
the wiring is as per the sierra original wiring. there are 2 wires at the top of the column which connect to the 2 pins which contact metal ring/dish
on wheel
hope this makes sense to you
steve
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Staple balls
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| posted on 21/7/12 at 11:39 PM |
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Probably talking arse here, been awake since 6am, Assuming no relay... check the continuity between the cable formerly known as neutral, and the
contact on the horn (mine at least has 1 contact, and earths through its body), if that's okay, the horn on your steering wheel should just be
switched live. easy.
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steve8274
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| posted on 22/7/12 at 08:18 PM |
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quote:
Originally posted by craig1410
quote:
Originally posted by steve8274
think i have tried that but will try again to be sure.
can you confirm that 1 wire should be positive and 1 negative. thats what i have anyway
steve
Well....I wouldn't put it quite like that as that would suggest that one is 12V and one is Earth which, if you switch them, would be a short
circuit. However, it may give the appearance of being 12V and 0V because the 0V will be earth and the 12V will probably come via the horn and since
there is no significant current flowing, the horn will not drop the voltage at all.
However, it is also possible that the one you describe as "positive" actually DOES come directly from the battery and the one you describe
as "negative" might go via the horn to earth.
If your original steering wheel was a simple, isolated switch then it wouldn't matter but the new wheel might only be compatible with switched
earth horns and you might have a switched 12V setup instead. It's easy to figure out what you have. If you disconnect all wires from the horn
(use tape to isolate them to avoid any shorts to chassis/engine) and then use a meter to check your "positive" wire, see if it is still
positive. If it is then that must be coming from the battery and you must have a switched feed setup not a switched earth. Another clue would be if
the horn uses a local earth or if it has two wires which both go back into the loom.
Let us know what you find.
C.
well i have been out to check car horn today and still no joy
i swapped wires round. no joy. thought i had already tried that
i disconnected the wires and when ignition switched on one wire is 12v and other shows as 0v
below is a link for some photos of setup. might be easier to see what i mean
not sure how to put pics on here
http://s825.photobucket.com/albums/zz178/highgranger/horn/
pic 1: horn switch
pic 2: wires to attach to horn. grey 12v yellow 0v
pic 3: 2 rings which 2 wires attached too
pic 4: 2 pins which 2 rings contact with
the horn was working fine with this setup using original sierra wheel
steve
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