twybrow
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| posted on 28/4/10 at 07:21 PM |
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Horn fuse keeps blowing
Evening all. As above, my horn fuse keeps blowing and I am rather stumped as to why. It doesn't use a relay, but it is a very quiet motorcycle
horn (enough for an MOT, but not really to warn people with!). It has worked fine (all be it quietly) for the last 2000 miles. Now, it has blown the
fuse, and I can't see why. If I hotwire the horn, it works just fine, but as I am mid way through a house move, I have very limited tools (no
multimeter). Can anyone give me some ideas as to what could be causing it? It had a 10amp fuse (I naughtily tried a 15 amp to see what happens, and it
blew that too!). Any help, greatly appreciated.
To be honest, I am tempted to leave it, as everyone can hear my car a long way before you can see it, so the horn is kinda academic - the problem is
it also supplies the indicators, so a blown fuse leads to hand signals, which isn't ideal!
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JoelP
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| posted on 28/4/10 at 07:25 PM |
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you never miss a horn til you really need it.
Most horns ive seen need 30A fuses? Yours sounds just like it needs a bigger fuse.
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Jon Ison
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| posted on 28/4/10 at 07:27 PM |
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Problem with the indicators ?
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perksy
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| posted on 28/4/10 at 07:52 PM |
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Dodgy Earth ?
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jonesier1
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| posted on 28/4/10 at 08:19 PM |
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does it blow with the horn disconnected ? or when you use the indicators ? your gonna need a meter and check for isolation of your wires or volt drop
testing is a good method (what you see is what you are loosing).otherwise its guess work unless you can spot a chaffed wire anywhere with a visual
once over.
im in my own little world...its ok though they know me there
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ReMan
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| posted on 28/4/10 at 08:34 PM |
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Short inside the steering wheel horn push did ity on mine, same symptom.
stayed like it for 3 years til i had to have an MOT till I looked to fix it and found it1!
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twybrow
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| posted on 28/4/10 at 09:16 PM |
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Indiators seem to work fine once the fuse was changed. Just seems odd that it worked all this time, then all of a sudden it doesn't. The joy of
the kit car I guess...!
I will try disconnecting the horn and seeing if it still blows. Good plan batman. I will have my trust multimeter by Monday, so the investigation may
have to wait until then otherwise. Thanks for the pointers chaps.
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dhutch
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| posted on 28/4/10 at 10:38 PM |
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Is it a sudden thing, or a 'worked in autumn bit not noe ive got it out the garage'
Daniel
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boggle
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| posted on 29/4/10 at 08:05 AM |
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steering wheel center horn..had loads of issues with mine earthing....
just because you are a character, doesnt mean you have character....
for all your bespoke parts, ali welding, waterjet, laser, folding, turning, milling, composite work, spraying, anodising and cad drawing....
u2u me for details
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twybrow
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| posted on 29/4/10 at 08:20 PM |
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It has worked with no issue, until a drive the other day. It has worked as recently as last week.
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Vindi_andy
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| posted on 30/4/10 at 09:59 AM |
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I would suggest youve got a direct short somewhere.
Its possible nay probable that there has been a wire chafing and now its gone through the insulation and touching chassis giving dead short
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02GF74
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| posted on 1/5/10 at 04:51 PM |
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quote:
Originally posted by JoelP
Most horns ive seen need 30A fuses? Yours sounds just like it needs a bigger fuse.
really?? 
just looked in haynes, z1000, 12 V 2.5 A
AFAIK horn technology has not changed much - there is eletromagnet that attracts a metal plate, the movement of the plate breaks contact to the
electromagnet so the plate springs back, contact is made nad it moves again etc.
The plate vibrates like a speaker and makes a tone.
There is either a wiring fault or a fault in the horn.
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David Jenkins
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| posted on 1/5/10 at 05:05 PM |
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What thickness of wire are you using to drive the horn? If it's a bit thin and/or a bit long then maybe you're losing some voltage and
the horn can't operate properly. If it doesn't pull back enough then it may be holding 'on' too long, which will increase the
current. When you wire the horn directly to test, do you use thicker wire, and is the wire much shorter?
I've often seen wiring manuals that say that heavy gauge wire should be used for horns, even if the actual current is quite low, to reduce
voltage drop.
Try putting a meter on the horn connector (with the horn still connected) and press the horn button - you should see very close to full battery
voltage.
Afterthought - also make sure that the earth connection is very clean and solid, for exactly the same reason.
[Edited on 1/5/10 by David Jenkins]
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twybrow
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| posted on 9/7/10 at 11:35 AM |
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Sorted - thanks people. It was a short inside the horn push/adaptor. It seems to be louder now too (still don't hear it over the exhasut
though!).
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