• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Horn help

Share this page

S

Sportsdoc

Jedi Trainee
Offline
I have all the electrical parts working....except the horn. I have a new horn, but suspect the problem is in the steering column. Basically the button just grounds the horn to make it work? Is there a usual culprit like the ground wire for the headlights?

Any tips appreciated.
 
Hi Richard,

Are you getting voltage at the horn(s)? Grab your handy multimeter or test light, and have someone honk the horn while you check. If no voltage, work your way upstream... (You've replaced all your fuses recently?)
 
The horn button and contact ring in the steering column get fried pretty easily by the high current of the horn. If you are indeed getting voltage to the horn, as the next test, I suggest hooking an ohmmeter to the horn terminal that gets grounded by the button (after disconnecting it from the horn, of course). See what the resistance is. If it's more than an ohm, the horn definitely won't work. Adding a relay to the horn is worth doing--it takes most of the current off the button and contact ring, so it is a lot more tolerant of an imperfect contact.
 
Fresh paint and a painted rack and column make for a bum ground. The horn grounds on the steering column which is bolted to the rack which is (was) insulated with paper gaskets around the clamps. Most likely it's a weak ground thru the steering column.
 
On the Mini I cleaned everything up and had good metal to metal contact everywhere required... even inside the horn button contacts. All I could ever get out of the horn was an anemic grunt. I simply couldn't pass enough current through the horn button itself for some reason. I installed a horn relay so only a few milliamps had to pass through the horn button and everything has been fine since. Horn relays did appear on later Lucas wiring harnesses... they are a good thing to add to cars built without them.
 
You kinda need to think different when thinking about the horn. When you look at the diagram, you will notice that the button grounds the horn. So, go to the horn and see if it has 12v. Ground the other side and see if it honks. I had to make an insulation ring to seperate the steering wheel from the contact ring to make my horn button work.
 
/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif

With botha y'all: Relays for getting a full 12V, using the horn push only for triggering the realay. Checking at the horn end the purple wire is voltage, the purple/black is the trigger ground. The horn should "meep" if you ground the P/B side.
 
Back
Top