Problem with horn wiring.

[ted_paper]

I have just disconnected my old horn with the intention of replacing it with a louder (hopefully) one.
When I fitted the new one - nothing. So I swopped it back for the old one  - again nothing.
I didn't check before removing the old one that everything was working so that was probably my first mistake...
As I have said on a previous post, electrics are a bit of a mystery to me. I have a multimeter which I am not entirely familiar but have established that my battery is fully charged, and if I stuff the 2 probes into the connectors to the horn, switch on the ignition and press the horn button then there is no reading showing.
Any advice where to start looking would be gratefully received.
Thanks 

[Johnwebley]

Does any of the switches in the left hand switch gear work?

Do you get lights and indicators?

Try and make a circuit tester,

Use a bulb holder, like fitted as the idiot lights, and get a couple of crocodile clips, that will make life much easier

Have you got a wiring diagram??


Good luck

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[ted_paper]

Yep, lights and indicators are working.
I have a Haynes manual showing the wiring, but I'm not sure how or what I should be testing... 

[Johnwebley]

If you can find a simple tester as I said, earth one lead to the motor or bolt head on the frame,

The other wire connect to a horn lead,press the button, hopefully the bulb will light,

Do this test on both leads,

Can you make out the colour of the leads?

Do they match the manual?

Have you tested the horn??



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[McCabe-Thiele (Ted)]

As John has said I would start by simply putting a test bulb where the horn was connected - if it does not light up with the ignition on & horn button depressed start checking for voltage in the circuit.

Some Hondas have the earth wire at the horn end with a live feed to the horn from the ignition circuit via the button. Other models have the button as the earth connection.

[Bryanj]

There are two different sets of wiring depending on year and model of bike, need to know both those before answering

[Athame57]

You might also want to check out my 'Horn of Death'    thread on CB400F horn wiring! http://www.sohc.co.uk/index.php/topic,27401.msg254773.html#msg254773

[ted_paper]

Bryanj           - It is a '77 model with 2 wires that look to be a green and a black.
John              - I thought I had a two-pronged bulb to make a simple tester - turns out I haven't so will have to get one at
                       Halfords! The horn(s)  have been tested and they are both working.
Athames57    - Thanks for the link - I've already looked at a thread going back to 2013 which went straight over my head!

Waiting on my lamp tester now.
Thanks

[Bryanj]

OK a 77SHOULD have one wire at the horn going to ground and the other supplying power from the switch IF everything is original which it may not be.
To be certain split the LH switch and see how many wires go to the horn button and report back.
Long distance elektrickery diagnosise takes time and patience, by the way you didnt say what 77 bike it was so i am still guessing

[ted_paper]

Thanks for feedback.
Grandchildren visiting this weekend so garage time is curtailed until Monday 

[Sesman]

Sorry if I have missed this, but what export market model is it? UK, USA, other?

[Mikep328]

Maybe I'm not understanding something but if you have a multimeter, why obtain a test light to check for voltage at the connectors?

[ted_paper]

It' a UK model
As to why to use a light test, I'm not familiar with the various settings on a multimeter and this might be an easier method?
Electrics are not my forte...

[McCabe-Thiele (Ted)]

If you go on U tube there are quite a few videos showing you how to use a Multimeter. TBH I use mine mainly on the DC volts setting range.

None of us are born electricians, it's a relatively easy skill to develop, you don't have to be able to use all the settings on a meter just a couple of basics will help you become more confident.

[SteveD CB500K0]

We can help with the multimeter.

Show us a photo of it and we’ll tell you what settings to use and what they should read.


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