Topic: Help with horn

[golden_child]

Well I've finally got my 72 cb750 running. But the horn isn't working. I am getting a multimeter today (or whenever I learn how to use it) to check the circuit to see if theere may be a short somewhere.

I've looked at the clymer wiring diagram starting from the horn to the regulator (front to back). Everything connected to that circuit is working correctly other than the horn and the electric starter switch. The electric starter needs a new solenoid I think or the cotacts cleaned. The PO said it was the solenoid, so I'll go wth that. Or is that something I should worry about for the circuit to be complete?

Here is my main question. Since everything seems to to be working on the circuit, Should I start my search from the horn button to the ground, then from the button to the horn? This is assuming that the horns are working. I have to check that internal circuit as well, I guess.

The horn is not oem. It looks like the line was spliced into 2 replacement horns.

Any help. I'm just a newbie trying to get this to pass inspection.

thanks.

[ProTeal55]

Worse case - re wire a direct power feed to the horn to get it to work for your inspection, then trace the issue...

[csendker]

The horn is not oem. It looks like the line was spliced into 2 replacement horns.

Splicing should always raise an eyebrow.  First I'd check to see if the horn's actually working or not.  Briefly hit it directly with 12V to see if it honks.  You can also check to see if you get juice to the horn when you push the button. Put your voltmeter on the leads to the horn: at rest 0V, push button and 12V.  I always like to eliminate the easy stuff first.

[Noel]

IMO, it's the horn itself that, nine times out of ten, is the culprit. I'd echo the advice to check horn function first.

[Kelvin8]

I fixed my non-working horn by attaching it to my car battery and honking it that way. My MC battery didn't have enough juice to free up the corrosion/oxidation, but the car battery did. It works fine now. To quote the Road Runner, "MeeMeep."

[mcpuffett]

ain't that beep beep    mick.

[golden_child]

So I got it going. I don't know what I did. It just started going be be be be BEEP. then nothing. Now it work if I have it reving at 1200 rpm. is that right?

[csendker]

No, that's not right.  It should beep whenever the key is on, bike running or not.  You may have a weak battery, not enough juice to operate the horn, but when you're revving it up, the alternator begins to overpower the battery (ie charges) and maybe then there's enough juice to honk.

[golden_child]

I put a new battery in it the other day. But didn't finish it off with a chtrickle charge. It's a wal-mart brand battery. What do you think I should do?

Also another odd thing I noticed today. The brake light is always on. I don't remember it staying on yesterday.

I'm getting all confused now.

[WiredForStereo]

Sounds like you have an old bike.

Check your brake light switches, my handle bar switch works intermittently so when there's someone behind me, I alwasy make sure to have my foot on the brake.

Secondly, check you foot brake switch, it may have come unscrewed and got jostled around, and may be stuck on.

You might wanna get on ebay and get ahold of some new wiring, the pod that contains your horn button, or whatever you might need.

[golden_child]

Thanks for the help and advise. I'll check the brake tonight and give the battery a full charge over the next couple days.

[Bodi]

Check if you have the 12V at the horn wires when you push the button, then track back from there if not.
The Clymer wiring diagram is a nasty confusing incomplete piece of trash. Check around the web for a factory service manual, the wiring diagram is absolutely complete although the way the switches are shown is a bit difficult until you get used to it. Honda4fun.com (?) has one online (pdf) - in Italian - but the quality is not superb. The wiring diagram is in the last part of the 350/500/750 manual.

[putnaja1]

Here's a couple things to check:
Always suspect previous wiring repairs!!  What you want to do with your multimeter is put it on the "continuity" setting- when you touch the two leads together the meter will beep- letting you know there is a closed circuit.  Use this setting to test the wires on each side of the splice, to make sure the splice is making good contact, and is not flaking out on you.  It could be that the PO just twisted the wires together and then covered them with tape- a sure "open circuit" at some point in the future- maybe the cause of your problem now.

To do splices right, do this:
1) Go to radio shack, and buy shrink tubing- you want to get the smallest size they have, probably 3/16" diameter.  Cut a piece about an inch long.
2) remove the electrical tape, untwist the wires, and slide your 1" piece of shrink tube onto one of the wires, and move it a few inches away from the joint.  Now re-twist the joint (if you have enough slack in the wire, cut off the old twisted bare wires, and strip off a 1/4" fresh on each side.  Twist them together so that the twist is inline, not perpendicular to the wire.
3) tin a soldering iron (let your iron heat up, clean the tip, then put fresh solder on the tip).  Now heat the joint, and press solder into the joint until it is nice and shiney.
4) slide the shrink tube over the freshly soldered joint, and heat it with a cigarette lighter until it shrinks tight covering the joint.  DONE!

Next place to suspect trouble (if it wasn't the splices) would be the connectors on that wire group.  Use the manual/schematic- it should show you where the connectors are.  Unplug them, clean/inspect the pins, and reconnect them, making sure there is good contact.  You can use your multimeter's continuity setting here to test.

Make sure your battery is fully charged too, just to be safe.  You also might want to check the continuity of the horn switch- make sure that when the horn button is pressed, your multimeter issues a steady beep.  Otherwise the switch might be acting up on you!

Jason

[TwoTired]

According to the schematic, the black wire going to your horn is 12v from the ignition switch.
The LG wire goes to your bars and the horn button provides a ground when pushed.  Beep.
Check for 12 volts on the black wire at your horn.  If this voltage is the same intensity as the battery plus terminal, and your horn still doesn't work reliably try a separate jumper wire from engine case or battery minus and every time you touch the LG horn terminal with the jumper it should beep.  If this gives you reliable operation, then your horn button contacts are probably corroded and need to be cleaned or replaced.
If the jumper causes the same behavior as the horn button, then the horn contacts internal aren't good.  Zapping the horn with a good strong battery and letting it blast for a minute or two might bring back the contacts and return the horn to full operation.  If not, replace the horn.

Cheers,