head scratching moment.. horn not working blowing fuses?

912UK · Mar 13, 2015

Hi there.. I have located the fuse for the horn and well it was blown...

I thought oh ,ok must be a dodgy wire or some thing..

I cleaned all the contact terminals to the horns, some where even very lose. Sorted all that and

nope blows fuses again!

I can hear a relay clicking in the fuse box and even with a blown fuse I can still hear the relay clicking so any one got an idea or had this before?

I was thinking this was an easy fix.. and it's funny how many idiots pull out in front of you when your horn is playing up!

912UK · Mar 14, 2015

No one then :-(

white944 · Mar 14, 2015

disconnect the horn(s) and see if the fuse still blows when you operate the switch.

peanut · Mar 17, 2015

sounds like you have a short to earth somewhere between the horn relay and the horns. Your horn push and relay coil circuit sounds like it is working correctly if you can hear the relay clicking.

If you have an alarm fitted its possible you may have had a connection made to your horn feed wire (Black /yellow) somewhere under your fuse relay board on connector N which is shorting

The horn fuse is fed from Terminal 30 which is a common 12v+ supply rail on the fuse /relay board.(Terminal 30 is fed directly from the battery.)
Terminal 30 on the horn relay is fed directly from this 12v+ common rail

To test the circuit feeding power to the horns
Remove the black/yellow feed wire to the horns .
Remove the horn relay
Put in a new 15A fuse F3
Check you have 12v+ on terminal 30 of the horn relay base.
Replace the horn relay.

Connect your multimeter between the free end of your black/yellow wire which you have removed from your horns and a clean earth point (ie the horn earth point) . There should be no voltage. Now press and hold the horn push and you should hear the relay click and see 12v+ on the multimeter.
If this checks out then the fault lies either with your horns (internal shorting) or the spade connector insulation on the horns where the black /yellow feed connects to your horns.

912UK · Mar 18, 2015

brilliant I will work though this..

yes it has an alarm but it's been on there for years.

OK I am going to test the horn with out wires connected ( brill idea )

will come back to you..

912UK · Mar 19, 2015

Ok I have done that...

disconected the horns and put in a fuse.. turned it all on and pressed the horn loads.. relay clicks in and out and it does not blow the fuse..

so I'm thinking that's the horn that's duff then.. of two horns only the one worked before anyway

peanut · Mar 19, 2015

yep that sounds like the problem ..
Good opportunity to fit something loud . A trip to a local breakers and you could test your circuit and try out a variety of different horns at the same time until you find something that sounds right and then order up some new horns

924nutter · Mar 20, 2015

you want to get a pair of AX gti horns. As they say in France, les Klaxons; formidable

912UK · Mar 20, 2015

http://www.ebay.co.uk/itm/331252709440?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I was just going to order these to be honest unless you see ones that are better.

mind you with the school run in the mornings!!!! it always amazes me, that normally educated well to do people, turn in to mindless, dumb acting brain deads in the mornings!

I rock up in my 944 or my W108 and park up and then I watch the chaos unfold! in 3 years I have seen 4 car crashes, 2 punch up's Stand off with a Skip lorry, DFS sofa delivery driver have a row with a set of parents OH and the old lady who has a blue badge rock up to the school 5 mins before the bell and parks on double yellows and for some one who has a badge because she can't walk very well, manages to do the school run for the last 2 years every say just fine! with a hobble..

yep I think your right I need one of these

https://www.youtube.com/watch?v=icnRMW6P9nc

wyn thomas · Mar 22, 2015

Did a new horn do the trick? And which horn did you go for in the end because I have the same fault atm?

peanut · Mar 22, 2015

ORIGINAL: wyn thomas

Did a new horn do the trick? And which horn did you go for in the end because I have the same fault atm?

Wyn its very likely that the horns are the root of the problem because they get so wet and muddy down there near the front chassis rail.

i would suggest that you check your horn fuse first, then remove and clear the horn earthing point on the chassis rail adjacent to the horns (brown wires )
If that doesn't do the trick then you are probably going to have to remove your horns and clean up all the electrical terminals as they get very oxidised and often have poor conductivity. Its almost impossible to see or get to the horns from under the bonnet unless you've got very small hands .[

]

Once you have removed the horns you can test them with a couple of bits of wire on a batttery.

If that all checks out then you are going to need to troubleshoot your wiring and relay circuit as explained at the beginning of this thread but do the other stuff first.