Technical Horn and relay (yet again) 2001 2.8 JTD

[LittleGreyCat]

I've looked through the threads on this subject, and learned that (after checking that the horn itself works) the most likely causes of faults are the relay and the connections underneath the steering wheel.

Vehicle is a Hymer motorhome registered in 2002 but AFAIK is on a 2001 2.8 JTD chassis - pre ODB2 connector.

Firstly, the horn works.

Checked with a mulit meter and as far as I can tell there is no voltage coming through to the horn push.

Before I set about removing the steering wheel I thought I would check the relay.
Following instructions here I took the passenger side lower plastic fascia off to reveal the relays.

However I have (I think) eleven different relays plus something white tucked around a corner.

Can anyone tell me, please, which relay is for the horn and how I test it.

I can post a picture if this helps.

Thanks

LGC

 

[Krosus]

Common fault, easily sorted. The contact ring under the steering wheel gets contaminated with grease, you have two options,
1. Strip down to horn contact ring and clean.
2. Install a horn push button.

I have heard that it is possible to clean the contact rings with hemp string by first remove steering wheel inserting string in between the rings and wrapping round boss. run back and forward until clean.


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[Krosus]

By the way the contact under horn push is negative the positive is to the lower contact ring, never known horn relay to go and like you I don't know which is which.


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[LittleGreyCat]

<snip>
2. Install a horn push button.
<snip>

To do that, wouldn't I need to find which is the horn relay and then intercept the wiring between the relay and the horn push?

I have been told that the relay is there to protect the horn switch from damage.

Cheers

LGC

 

[LittleGreyCat]

Just realised I haven't followed this up.

Turns out the steering wheel is really easy to remove and refit, and the problem was in the connection under the horn push.

Easy to check by bridging the contacts with the wheel off.

This even fixed a problem I had with the self cancelling; I think the steering wheel had been off before and not put back quite right. Removing and refitting has fixed it.

 

[BarryE]

Just realised I haven't followed this up.

Turns out the steering wheel is really easy to remove and refit, and the problem was in the connection under the horn push.

Easy to check by bridging the contacts with the wheel off.

This even fixed a problem I had with the self cancelling; I think the steering wheel had been off before and not put back quite right. Removing and refitting has fixed it.

How do I remove the steering wheel cover to clean the horn contacts, its not the horn thats new as from today and has electric, it is in the steering wheel.
Help please,

 

[LittleGreyCat]

How do I remove the steering wheel cover to clean the horn contacts, its not the horn thats new as from today and has electric, it is in the steering wheel.
Help please,

A good while since I did this, however I will try and remember.

Please note that this is for a steering wheel WITHOUT AIRBAG!
If you have an airbag in the steering wheel seek professional help.

As far as I recall, you just carefully prise the plastic bit off the centre of the steering wheel (the horn push). At this point you can put a multi-meter across the contacts under the horn push to confirm that there is no electricity getting to the contacts. If there is electricity there then look elsewhere for the problem.

You should then see a big nut holding the steering wheel on.
Undo the nut and the steering wheel should lift off.

Be careful, before you start, to have the front wheels pointing directly forward so you can get the steering wheel back on correctly aligned.

Also note how the self cancelling mechanism is fitted so you can put that back correctly.

You should then be able to test the horn using the contacts underneath the steering wheel, and also clean up the sliding contacts under the steering wheel. Do test that the horn works when you use the contacts on the steering column. Again, if the horn doesn't work then look for another cause. No point in putting the wheel back on then wondering why it still doesn't work if the contacts weren't the problem.

The horn push closes a contact on the steering wheel. This then connects to a sliding contact under the steering wheel which connects to a fixed ring on the steering column. This allows the horn to work and the steering wheel to turn without worrying about twisting wires. My problem was the contact between the sliding bits - quite a common problem as I understand it.