Found & Removed the Horn but Where's the Fuse - Ducato 2.8 Year 2000

[StitchUp]

Horn hasn't worked for ages and when it did it sounded like a fart in a gale!!

So, I found and removed the horn (easy) and tested it across a 12v battery - sounded awful! Prior to removing the horn I removed the steering wheel horn depress pad and shorted the wire that attaches to the top/pad to the contact below and nothing!

So I'm thinking the fuse - there's a row of fuses in the glove box but not sure which, if any, would be the horn fuse. I'm informed the relay - if there is one, rarely fails.

Also, the step stopped working following the last MOT probably about the same time as the horn, not sure if the two (horn & step) are connected in anyway.

Any help appreciated

 

[Manic]

Fuse is highlighted in blue under cover in glove box

 

[StitchUp]

Thanks so much, I'll be checking that in the morning Looks like that fuse is for the electric windows too and mine work okay!

 

[StitchUp]

Checked the 25amp fuse and all was good, measured 12v across the fuse too.

I was expecting to find 12v on the insulated terminal that connects to the 'depress' pad but there was nothing and no continuity to earth either! Anyone know whether I should find 12v on this connector?

Cheers

 

[Landy Andy]

Checked the 25amp fuse and all was good, measured 12v across the fuse too.

I was expecting to find 12v on the insulated terminal that connects to the 'depress' pad but there was nothing and no continuity to earth either! Anyone know whether I should find 12v on this connector

I think the live 12v, is run to the horn and all the switch side is negative. So you won’t find a supply there.

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[GeoffnDee]

I think you will find there is a relay for the horn it is in the under bonnet fuse box , the middle relay on the top row of relays. (R4) and would be worth checking as it would be the link between the horn push and the horn.

 

[StitchUp]

I think the live 12v, is run to the horn and all the switch side is negative. So you won’t find a supply there.

I did wonder that, I have ordered a replacement horn so will leave things until tomorrow.

I have read somewhere that often the issue is with the contact beneath the steering wheel getting dirty so I'm at that point of removing the steering wheel! Of course, if the relay isn't working I won't be finding 12v at the horn until the relay is activated.

I'll end up an expert on horn repairs for early versions of Ducatos

Thanks

 

[Landy Andy]

I would think that either the copper plate in the wheel should have continuity to earth, or the termina in your pic. The other copper plate, or terminal should go to the horn. I assume you don’t have earth to either? Often the fail is the clock spring that is under the steering wheel where you have contacts that rotate, and get covered in crap, and wear out.

 

[StitchUp]

I think you will find there is a relay for the horn it is in the under bonnet fuse box , the middle relay on the top row of relays. (R4) and would be worth checking as it would be the link between the horn push and the horn.

Can't find the 'under bonnet fuse box'!

There's a fuse board in the glove box but there's no relays at that location!

Any ideas where I might find the relays bearing in mind this is a year 2000 Ducato. Nothing flashes at me beneath the bonnet!

 

[Manic]

The relays are under the bottom part of the dash, the part the speaker is, so directly under the fuses.
2 screws in front of fuses, visible when you’ve took the glove box lid off , one in lower cubby hole and one near wheel arch.

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[GeoffnDee]

StitchUp Sorry but the diagram I have shows a fuse box (with relays) on the right under the bonnet and was supposed to be for X230/244 models but it does not seem to be there in your case, That is where the horn relay was shown to be located but maybe your van does not have the horn relay after all ? (unless it is where Manic has suggested)

 

[StitchUp]

Just found this picture somewhere else on the forum - not mine but what a birds nest!! I'll get to them in the morning and then I'll need to ID the horn relay & part number to replace it.

 

[Landy Andy]

You may not have a horn relay on that age.

 

[StitchUp]

You may not have a horn relay on that age.

As I have 12v to one side of the horn and no earth continuity to a good chassis earth on the other terminal, even when I short the horn wires beneath the depress pad on steering wheel, I'm thinking the relay may be the culprit - I also physically shorted the two wires beneath the horn depress pad but still no earth on the other terminal to the horn!
I could be 'barking up the wrong tree', but it's worth a shot.

 

[Landy Andy]

In my opinion if there was a relay in the system then the relay would control the live too the horn, not the earth. It may, and probably would be switched by the earth switch in the steering wheel, but wouldn’t switch earth on and off to the horn it’s self.

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[StitchUp]

In my opinion if there was a relay in the system then the relay would control the live too the horn, not the earth. It may, and probably would be switched by the earth switch in the steering wheel, but wouldn’t switch earth on and off to the horn it’s self.

You're likely correct Landy Andy. Horn is now working .
I removed the panel today revealing the relays and one by one carried out basic test to ensure each was switching when 12v & earth was applied. All but one was switching.

The one that wasn't switching was the black relay on top row 46409709. Not sure what this does - maybe central locking that has never worked since I purchased the van 14 months ago.

The horn hasn't worked since the last MOT nearly a year ago despite me asking them to fix it, anyway, I've made off the cables attaching to the horn with new connectors and soldered them. I also replaced the horn with a new one. I then removed the steering wheel and tested the two contacts that establish a circuit when the pad is depressed. I checked that one of these contacts, the earth was reaching the horn terminal - it was , I then shorted the two prongs and the horn sounded I bent the prongs upwards so they'd make a good contact with the brass disc and cleaned all with a contact cleaner spray cleaner and some fine emery cloth and reassembled everything.

I now have a loud, working horn

Thankyou everyone for your help and comments.

Now I need to get the step working, this also failed following the last MOT!

John

 

[StitchUp]

This shows the brass disc on the underside of the steering wheel to which the two contacts make a connection, I understand this can be a common problem. The red tape is so I can realign the steering wheel on the column precisely.

 

[Landy Andy]

I thought it would be the clock spring

Often fail as it’s a moving part. Glad your sorted.

Can you not jump the no functioning relay and see what works??? I would have to know.

 

[StitchUp]

Can you not jump the no functioning relay and see what works??? I would have to know.

If I get time, I'll do that tomorrow