Horn wiring...

[buxtonmick]

Next thing that's puzzling me is the wiring for the horn.  The diagram indicates Light Green going to a dot inside the broken line and I have no idea what that means.  Also, the only spare wire from the loom that I have is a very pale mint green colour.  I presume that the green wire with the ring connector is to earth?  I'm not far off finishing the bike now so help with these last puzzlers is greatly appreciated!

Ta, Mick.

[ka-ja]

Hi,
     The dotted line represents the main loom (I think) but if you look carefully the light green  also goes out of a double connector back to the horn button as well as into the loom (dead-end?) and the black goes to green and the earth ring-----Ken

[ashewan]

The diagram indicates Light Green going to a dot inside the broken line and I have no idea what that means.  Also, the only spare wire from the loom that I have is a very pale mint green colour.  I presume that the green wire with the ring connector is to earth?  I'm not far off finishing the bike now so help with these last puzzlers is greatly appreciated!

Ta, Mick.
[/quote]
HI
Broken line outline indicates the loom and LG coming from horn should connect to LG (or similar in your case in the 'big rubber thing' left side front frame; that eventually ends up at the horn button. For the other horn terminal then in my case I took a black wire with connector to 'your' green wire with ring and connector and bolted the ring under one of the bolts holding the horn; making sure there was a good earth to the frame.
Works for me.
Andrew

[Lobo]

I think the 'dot inside the loom' you're referring to is simply a permanent connection.. think of it as a blob of solder!

On these old Hondas, and according to my wiriing diagrams:

A RED wire is permanently live (+ve), ie 'hot wired' to the battery.
A BLACK wire is switched live, ie only +ve when you turn the ignition on.
A GREEN wire is permanently grounded (-ve). Ie at all times connected to the -ve terminal of the battery, via the frame.
A LIGHT GREEN wire is switched earth, ie only connected to the frame when you press the horn button.

So, using my diagrams. One side of the horn has a black wire (ie +ve when ignition on) and the other side of the horn has a light green wire.... which connects to earth when you press the button, completes the circuit & sounds the horn.

BUT. A change of switchgear can nullify the above, eg if off a later model / different CB. In which case the above circuit may not be quite correct.

Bottom line simply...

Connect a switched live (+ve) ... should be a black wire... to one side of the horn
Connect the light green to the other. If it doesn't work then no harm should be done.

If this doesn't work your set-up / switchgear is likely non-OEM and then you should try..

Connect one side of the horn to (permanent) earth (by the book should be a green wire to the frame!)  and the other to the light green.  If it works great, if it doesn't then no harm will be done as you'd be simply putting two earths across the horn.

(Comment: NEVER simply connect an unknown loom wire directly to +ve or -ve, ie always have 'something' in between, such as a horn / lightbulb.... or best of all, a multimeter! (See below)

A fantastic tool, and from £5 upto £500 is a good old multimeter.  Will save an awful lot of time / tears. Typically you can...

Test for continuity... ie is this end of the wire connected to this wire at the other end of the loom? Or is this wire earthed? Buy a meter with audible beep to make this job a breeze.

Test for voltage... Eg is this wire perm live, or switched live? Connect one lead to your wire, the other to the frame & check to see if 12V permanently ... or only with ignition.

Test for voltage regulation.... Put the leads onto the battery & rev the bike... read the voltages against RPM & check within spec.

Test for current consumptions, battery drain... 'Break' the circuit and put the meter leads in between.. and read the amps flowing. (many meters only do milliamperes, choose one that can read upto 10A.

The list is endless... and it ain't as daunting as it all might seem.

First one I found on ebay...

http://www.ebay.co.uk/itm/Digital-LCD-Multimeter-Voltmeter-Ammeter-AC-DC-OHM-Volt-Tester-Test-Current-/160994004691?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item257bfd8ed3

Good luck,
Simon

[mickwinf]

The 400 may be the same as the later 550s with a horn/flasher button which doesn't earth at the switch, but connects the light green wire to a + supply when the button is pressed, so giving power to the horn via the l/g wire, then from the horn to earth via a short wire grounded on the horn mounting bolt.

[ka-ja]

Hi,
     I tend to agree with Mickwinf, I have three different wiring diagrams for the 400/4, and they all show the light green as a switched supply from the horn button, and the black changing to earth green via a bullet connector then to earth----Ken

[Lobo]

Forgive me...

Been hunting down further circuit diagrams, and found one indeed, where the Light green is a switched live, and thus the other side of the horn is earthed. Why would Honda make the wiring (on same models / different exports?) so different!

As such, you (nay, I!) perhaps must be cautious of 'Internet' circuit diagrams... I stand by the recommendation of a good old multimeter to confirm your actual wirings rather than what you think you might have.
Cheers again
Simon

[buxtonmick]

Thanks for all the input folks, I'll try to find time tomorrow to make further progress.  As you say Simon, the proper way is to pull the switch apart and check with the meter for the correct wires.  I must say though, I'm still confused about the wire ending in the dot!

Thanks, Mick.

[Lynx]

Does the horn need earthing?
I had two horns from Classic Motorcyle Spares in Spalding. Neither seemed to work. Not even if I connected the horn terminals directly to a new battery. I sent them back and they said they both work fine. They are 12 volt.
What am I missing.

[steven400/4]

mine has earth to horn bracket

[Lobo]

Bad luck Lynx..

To check your wiring simply put a 12v bulb between your horn feed wire & earth. It should light when you press the horn button... (Ignition on!)

These horns can be very voltage critical... depending on the adjustment screw. If not set up & voltage just slightly low all you might get is a 'click'.... often not noticed as mostly horns used with the engine running... ie with circuit voltage up around 14V ... instead of (eg) 11.5 with a tired battery. What I'm suggesting here is your test battery possibly a bit low?

Regardless, on your 'next' horn try loosening the adjustment bolt at its rear, and using a screw driver adjust to the point you get a good loud beep at all voltages.

[Bryanj]

The change from button earthing to button supplying power wasn't by market but by year of manufacture, trouble is people think of year of registration as manufacture when the crate could have sat for years between manufacture and sale

[Lobo]

Ah! That's interesting Bryan... explains things; I thought it was dependant upon market destination. Makes life a litte more complicated renovating due DSS replacement wiring looms etc may well be different spec to your handlebar switch set-up: speaking from experience with my K2.

[Lynx]

BTW my horn works now. Tested direct to the battery just as before but this time makes a sound. Then fitted to bike and it still works  . I guess the guy at Classic bike spares tweeked the adjusting screw before sending it back.
Thanks for all the useful info.