Author Topic: 78 cb750 wiring help on NH seacoast (Read 7683 times)

sethmcalister · « **Reply #50 on:** July 17, 2014, 04:22:32 PM »

Alright....horn works hooked directly to the battery. How do I check the wiring from the switch to the horn to see if it is that or the switch? I do t want to have to buy a new switch if it ends up being the wiring.

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calj737 · « **Reply #51 on:** July 17, 2014, 05:15:51 PM »

Sorry, had to re-read this thread to get current.

Are you using this wiring diagram when you compare your switch wiring? I know the harness is aftermarket-

Earlier, you mentioned you weren't sure if the L switch was grounded. You indicates the green left the switch, but went to the horn. Per the diagram, the switch itself also needs to be grounded.

If I read this diagram properly;
Your switch (horn button) interrupts the power to the horn by "grounding" it when HORN is depressed. But in order of it do that, there must be a path to GROUND for the switch. The horn has one at the horn unit, but the way you're wired at the switch with the new harness, your switch may not be. Any chance you can snap a couple of pics?
-Of the unit
- of the wiring leaving the switch
- the harness connections for the switch

I'd like to see the colors to get a better visual. I know you're frustrated because you're so dang close, but realize, you're SO very close!

sethmcalister · « **Reply #52 on:** July 17, 2014, 05:52:21 PM »

The pictures are dark, but I hope you can see them okay. So light green coming out of the switch going to the connector (don't pay attention to the splice). The light green goes directly to the horn where you can also see black and green (ground). The horn has two connectors and what appears to be a screw for a ground. However, the diagram shows positive and negative and not the screw.

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calj737 · « **Reply #53 on:** July 17, 2014, 06:07:31 PM »

The horn has the proper two poles for attaching the ground wire, and the power wire. A the package shows (schematic) from the switch to the horn with 2 wires. But, it also shows that the control switch just be grounded.

The bundle of wires you're holding are coming from the left control? And this is a picture from within the headlight bucket? If so, I'd like a slightly better/different picture. Show me the connector where the control plugs into the harness so I can see both sides of there colored wires please.

Also, tell me that's not the helmet you're planning to wear on the ground below your bike! You should wear a full face

sethmcalister · « **Reply #54 on:** July 17, 2014, 06:21:50 PM »

Yes, they're coming from the left control. The schematics for a 78 should just be black and light green. Yes, they're in the headlight bucket. I'll try to get a better shot of the wire coming out of the control but it will have to be tomorrow and the wires are pretty well covered.

You like my daughter's helmet? I thought about wearing it here and there.

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calj737 · « **Reply #55 on:** July 17, 2014, 06:25:54 PM »

I'm leaning towards you needing to open the left control switch to locate the "short". Just so you know...

Your horn works, the wires are present, so somewhere between the horn and the button is the problem.

sethmcalister · « **Reply #56 on:** July 17, 2014, 06:45:37 PM »

Alright. I had it open yesterday and it looked good. How do I test it?

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madmtnmotors · « **Reply #57 on:** July 17, 2014, 06:56:05 PM »

Quote from: sethmcalister on July 17, 2014, 05:52:21 PM

the diagram shows positive and negative and not the screw.

The screw is not an electrical connection...

The test for the horn button is a simple test for continuity (when the button is pressed). This can be checked at the leads without dismantling the controls.

sethmcalister · « **Reply #58 on:** July 17, 2014, 07:03:16 PM »

Alright so the connectors (for the horn)...I attach black from the multimeter to the control light green at the horn connection and red to the black connection. Key off, continuity test, correct?

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calj737 · « **Reply #59 on:** July 17, 2014, 07:08:41 PM »

Nope. Continuity is within the same wire. Probes at either end of same wire. Black probe at horn green, red probe at switch green. That verifies current along a wire.

What you were describing is a current "test" where you'd measure for voltage. And you should. Both at the thorn, and at the switch itself, where the horn contacts are.

madmtnmotors · « **Reply #60 on:** July 17, 2014, 07:18:21 PM »

Quote from: sethmcalister on July 17, 2014, 07:03:16 PM

Alright so the connectors (for the horn)...I attach black from the multimeter to the control light green at the horn connection and red to the black connection. Key off, continuity test, correct?

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>Key off, switch disconnected.
>Set the multimeter to "ohms" or "continuity".
>Provided that the light green wire is the one from the horn button, it doesn't matter which lead goes where, just connect one lead to the light green wire (from the switch) and the other lead to ground. Any ground will due, either ground it to the frame, engine, or the green ground wires in the main harness. Might want to check continuity of your main harness ground wires while you're at it (from harness ground wire to frame or engine).
>Press the horn button to test for continuity between light green and ground.

Viola'! Multimeter 101.

The horn button completes the ground circuit to the horn to complete the circuit when the button is pressed. DC voltage 101...

sethmcalister · « **Reply #61 on:** July 18, 2014, 02:43:20 PM »

Checked continuity of the main harness ground wires and I'm good there.

However, no continuity for the switch. Here is the picture showing the wire connecting into the switch (I cannot get the screw out and have begun stripping the head). So looks like I need a new switch then, right?

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sethmcalister · « **Reply #62 on:** July 18, 2014, 02:46:26 PM »

Can I just run my starter wires into the horn wires since I usually kick? I don't want to have to buy a switch for $50 just for the horn. Or do you guys have another suggestion?

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calj737 · « **Reply #63 on:** July 18, 2014, 02:54:56 PM »

You have no continuity from the switch to the harness plug for it? If not, then somewhere along it's length is a short. Changing switches won't cure that.

Try an "easy out" which is a left hand drill bit. Pick up a cheap set at the home center. The screw is soft metal and will turn right out pretty quickly. The contacts look a little dirty but without continuity, your problem is the wire. If you had continuity, but no function, then it's the switch.

Make sense?

sethmcalister · « **Reply #64 on:** July 18, 2014, 03:14:31 PM »

Shouldn't there only be continuity when the button is pushed? When the button is pushed there is still no continuity, why wouldn't it mean that it's not the switch?

If I just picked up a toggle switch and ran a new wire that would temporarily solve both potential problems right? Or should I not go that route?

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calj737 · « **Reply #65 on:** July 18, 2014, 04:58:53 PM »

Continuity doesn't require any activation from a switch, current does. The probes on either end seek each other and send a signal to and from. Your meter registers if it's received. Basically.

If you put red probe on black at switch, then black probe on ground, and push the switch, you should see 12v. If not, your switch is not activating.

sethmcalister · « **Reply #66 on:** July 18, 2014, 05:51:22 PM »

Then Wilbur explained the continuity test incorrectly? Red and black probes should both be on light green to ensure continuity through the wire, right? Not one on light green and the other on ground.

That being said, I have not confirmed whether or not light green has continuity. I'm really still leaning toward a bad switch.

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calj737 · « **Reply #67 on:** July 18, 2014, 05:55:42 PM »

No, he was correct in orientation. He was indicating on how to test your light green at the switch for continuity to ground. I want you to test the black wire at the switch for power, and for continuity to the horn.

Worst case, I'm heading to Keene next Sunday. I'll stop by Monday on my return and we will get this straightened out.

sethmcalister · « **Reply #68 on:** July 18, 2014, 06:24:11 PM »

Alright so voltage on black at the switch and then continuity on light green?

I def appreciate it, but Keene is still quite a drive from the seacoast.

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madmtnmotors · « **Reply #69 on:** July 18, 2014, 06:28:57 PM »

Quote from: sethmcalister on July 18, 2014, 05:51:22 PM

Then Wilbur explained the continuity test incorrectly?

I kind of thought the term "continuity" was self explanatory... i.e. "continuous" unbroken connection.

Check the meter first. In the "ohm" or "continuity" setting, touch the meter probes together and see if your meter will even test continuity. Most meters require a battery for this function, and if your meters battery is dead this function likely will not work.

The horn switch completes the circuit to ground, so activating the horn button should complete a continuous (continuity?) connection to ground.

Quote from: calj737 on July 18, 2014, 04:58:53 PM

Continuity doesn't require any activation from a switch, current does. The probes on either end seek each other and send a signal to and from. Your meter registers if it's received. Basically.

The current generated by the battery in the meter when testing "ohms" or "continuity".

Multimeter 102...

Quote from: calj737 on July 18, 2014, 05:55:42 PM

No, he was correct in orientation. He was indicating on how to test your light green at the switch for continuity to ground. I want you to test the black wire at the switch for power, and for continuity to the horn.

To check the light green wire, set the meter for "ohm" or "continuity" and touch one probe to one end of the light green wire in the headlight bucket and the other probe to the other end of the light green wire where it connects to the switch. This will tell you whether the light green wire is broken or not. Then continue to proceed with the aforementioned test for continuity across the switch itself.

There is no black wire at the horn switch, unless you are referring to the black wire from the ignition switch. To test the switched voltage (ignition switch) with the ignition switch on, the black wire at the horn should read 12v (or any black wire in the harness for that matter), meter set to read DC volts, red probe to black horn wire, or any black wire for that matter. I know, red to black is counter intuitive (black is hot, go figure). Then connect black probe to ground (or any green wire), and again, ignition switch on will test the voltage supply to the horn and numerous other circuits..

Read carefully. Electrical circuits are simple logic circuits... which means they aren't very understanding when wires are crossed!

Which also means do not try to test for ohms or continuity on an energized circuit. You can fry the meter...

When testing for continuity you will want to make sure the ignition switch is off, and you can even disconnect the battery to be absolutely certain if you are unsure about any of the procedures described above, or in the link below:

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&sqi=2&ved=0CE4QFjAE&url=http%3A%2F%2Fnadp.sws.uiuc.edu%2Fcal%2FPDF%2FMultimeterUse.pdf&ei=98vJU67EJpLNsQSm1oGoCg&usg=AFQjCNFV6VPvPy0vTWBEGGc6gXk0KIJxjQ&sig2=GxFMhYD6kv1aElHubfXHhA&bvm=bv.71198958,d.cWc

calj737 · « **Reply #70 on:** July 18, 2014, 06:43:39 PM »

Quote from: madmtnmotors on July 18, 2014, 06:28:57 PM

There is no black wire at the horn switch, unless you are referring to the black wire from the ignition switch.

Right! Sorry, brain fart on that. I think he already tested black for power at the horn, had 10.x then after a recharge had 11.x. So we know he gets switched power. The ground path from switch is the issue now.

sethmcalister · « **Reply #71 on:** July 19, 2014, 03:01:02 PM »

Alright so I have continuity for the light green. Checked it from where it connects at the switch to where it would plug in at the horn. So I have power at black and continuity without depressing the horn button from the switch to the horn.

Bad switch now?

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madmtnmotors · « **Reply #72 on:** July 19, 2014, 03:18:17 PM »

Quote from: sethmcalister on July 18, 2014, 03:14:31 PM

Shouldn't there only be continuity when the button is pushed?

Yes

Quote from: sethmcalister on July 18, 2014, 03:14:31 PM

When the button is pushed there is still no continuity, why wouldn't it mean that it's not the switch?

It would either be the contacts in the switch, or the switch is not grounded. Did you attach the switch housing back on the handlebars for the continuity test? I believe the switch is grounded through the switch housing to the handlebar.

calj737 · « **Reply #73 on:** July 19, 2014, 03:30:49 PM »

Quote from: madmtnmotors on July 19, 2014, 03:18:17 PM

It would either be the contacts in the switch, or the switch is not grounded. Did you attach the switch housing back on the handlebars for the continuity test? I believe the switch is grounded through the switch housing to the handlebar.

It is grounded via the bars. Seth, your problem lies in the switch itself most likely. But you do need to verify the last test listed above.

sethmcalister · « **Reply #74 on:** July 19, 2014, 04:28:04 PM »

I did not reattach to the bars...how do I test the wire at the switch if the switch is reattached at the bars; I wouldn't be able to access the the wire soldered to the switch if the controls were reattached. Am I misunderstanding something here?

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Author Topic: 78 cb750 wiring help on NH seacoast (Read 7683 times)