Intermittent horn electrical conundrum

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purplechugster
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Intermittent horn electrical conundrum

Post by purplechugster »

I knew me saying on another thread that my horn was fixed was doomed to catastrophe :roll:

So, suggestions please....

My horn works fine when the engine is running, but not if it isn't (could happily live with that, except its the MOT next week). The horn has been replaced (twice), and I dont think its the switch because if I take the switch apart and 'manually' stick the wires together I get nothing. Also, when the horn button is pressed, I can hear the horn 'clicking' like its trying to beep, but not managing it.
Then of course, every now and then, it beeps fine :?

Thought it might be the voltage to the horn, but charging the battery makes no difference :(

Any ideas? Getting urgent!
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dbroada
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Post by dbroada »

check the voltage at the horn. One wire should be 12v (ignition on, not neccessarily engine running). Connect the other terminal to chassis and it should sound. If it doesn't it's the wiring to the horn that's your problem. If it sounds then it's the wiring to the push button or (more likely?) the earthing of the horn push to chassis. The wire can easilly break at the bottom of the steering column.
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purplechugster
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Post by purplechugster »

Can't find anything obvious.

And I havent got a voltmeter, so yet another trip to Halfwits required :roll:

One more thing... or rather two...

There's an 'over-ride' switch for the fan (or at least a fan), which works brilliantly, but also only runs when the engine is running. Otherwise theres a screeching unhappy fan noise.
AND... when I bought the van he mentioned that the wiring had been jigged about so the radio/CD player could be on when the ignition wasnt (apparently you cant normally. Is that true? ). Maybe thats got something to do with it?
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Cate
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Post by Cate »

I had an intermittent horn problem, after advice from Pete/Headley18 I checked the wiring at the bottom of the steering column, (take the cowl off) mine was mostly broken and finding contact sometimes.
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Post by dbroada »

without a multimeter I would start with Cate's suggestion - which is probably where I would start anyway. :D

Which fan are you talking about? The engine cooling fan is controlled by the radiator temperature. My heater fan has 3 positions, the fastest of which has to be positioned just right for it to work, and it only works with the ignition on.

My radio is wired to play without the ignition. I thought that was standard!
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tonytech
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Post by tonytech »

Errrrrrr.....

According to my Bentley the horn is fed from a ignition switched live.

This means the horn only works with ignition on.


Dont shoot the messenger :D

T
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horn inop

Post by angry vanagon »

do you have twin tone horns or a single tone, if you have twin tones on with no horn relay the horn push can't make a good enough contact to sound the horn properly.it sounds like a poor earth the easyest way to check this is switch ignition on pull the brown wire of the back of the horn get a piece of wire with the ends stripped touch on end the the van body unpained metal work or bolt head and the other to the connection on the back off the horn if it works you have a good live feed and horn you have lost your switched earth most probebly on the column if the horn doesnt work you have lost your live + (check fuses) or have a faulty horn unit
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Post by sendiw »

You say someone has been fiddling with the electrics.
Do you have a leisure battery or has the van ever had one? If so it could be that they have made a mistake with the wiring and your horn/blower are picking their feed up via the relay(which is only live when the engine is running)??? Just a thought and I am no expert.
good luck.
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purplechugster
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Post by purplechugster »

All good ideas... keep 'em coming... I'll be back in/under the van tonight... :roll:

Just to clarify - the horn works when the engine is running, but not when the ignition is on but the engine is off.
Makes me suspect the wiring, rather than an earth, as it works 100% when the engine is running.


But, then agan, I can hear it making some kind of contact at the horn, and it does work every now and then!

Normal horn so not a two-tone issue.
Yes, it does have a leisure battery, so might be that.


...Or something else! :roll:
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tonytech
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Post by tonytech »

OK. Looking at Haynes wireing diagrams, The horn push completes the circuit to earth for a relay in position No6.
The live for this circuit comes from fuse 15 which also feeds the brake lights.

The contacts of this relay complete the circuit to earth for the horn.

The only link I can see between the horn problem and your fan noise is the earth tag next to the fuse box.
These tags can get corroded and cause a loss of voltage at the device being powered.

A fully charged battery will give 12.5V. A battery being charged by the engine running Will have 14.5V accross it. The extra voltage may be enough to overcome the resistance at the tags.


T
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purplechugster
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Post by purplechugster »

Hmmm, thanks for that, that sounds promising... :D

It has felt like the horn wasnt getting enough juice - when it had a brief phase of working yesterday morning, it still wouldnt do it while the glo-plugs were charging, so maybe the 12v versus 14.5v is the key.

I'll clean up the tags, earths etc later tonight and get back to you!
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Post by ermie571 »

Hi,
Had intermittent horn. Gave up trying to fix it...

went to maplins got a push button and dirctly wired the horn to the battery with the relevant fuse. The additional button was put on the pod above the handbrake light.

Went through MOT fine as can reach easily!

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Post by Mocki »

now, if this was me, the first thing i'd do would to be take the steering wheel off, and clean the horn ring on the back of it, and its static contact it contacts with.....

i'd them look at the connection at the bottom of the steeing col, and replace the spade connection there, they go loose.

i didnt catch the year of your van, but clean the fuse contacts too, the early ones need a "roll" now and again because they tarnish.......
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Post by geordie skydiver »

tonytech wrote:A fully charged battery will give 12.5V. A battery being charged by the engine running Will have 14.5V accross it. The extra voltage may be enough to overcome the resistance at the tags.


T

This is almost certainly your problem.

Past experience and all that... :oops:
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purplechugster
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Post by purplechugster »

Iffy horn update... :roll:

Checked the wiring on the steering column - no apparent problems there.

Cleaned the tags, earth wires etc - no joy.

Fiddled with fuses and they look like there's good contact.

Taken off the steering wheel and cleaned up the ring thing and contact.

...And all I get is the horn 'clicking' but not actually beeping :cry:


I noticed something else as well - when I first start the engine, the battery light remains on, til I give it a rev, presumably 'cos the belt is a bit loose. And the horn doesnt work til Ive given it that rev. So it looks like we're on the right track with the power voltage idea.

But nothing Ive done has helped so far!!

What next people?
Temporary bodges acceptable - will temporarily wiring a 6V horn to the van work? :?
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