Topic: Any wiring specialist ? electrical break down CB 750 K2

[aminemed]

Hi

I installed (or at least tried) to install the m flash from motogadget as per the instructions in the attached picture, for a CB 750K2: m flash red wire should wire with bike 12v and m flash black wire should be wired with bike ground, but I did it wrongly. Instead I hooked bike black wire with m flash black wire (supposed to be wired with ground) and bike gray wire (turn signal main) with m flash red wire (supposed to be wired with +12v wire) then....boom! No more lights, no more electrical start at all in the bike even when I removed the m flah and went back to my original wiring scheme with my old flasher. Any thoughts on what happened ? (i changed the fuse) Now only thing i get is that engine turns over (i can hear it), but there is no ignition.

[evinrude7]

i couldn't tell you but one thing i did notice.  english isn't the instruction author's first language.  no offense to those who's first language is not english. 

[540nova]

It's from Germany. The M-unit instructions are somewhat lacking in clarity.

Sent from my SM-G955U using Tapatalk

[Phinn]

The solution is to learn German and read the instructions as originally written. Alles klar!

[Mr. Mike]

I'm no electronic wizard, but this is my observation;
I don't understand your "black to black" hook up as black on the bike is 12v right?. This unit appears to be in series (or inline) with the grey wire. Sounds like you might've  put 12v to the negative side of the unit for a direct short.
I'm thinking it should look like this;

[flasher relay]-grey--><MFred---[MFUnit]---MFBlk><---grey----->>>>turn signal swx.

Anyone have anything else to offer?

[aminemed]

That's what I did. After my mistake, i connected the black +12v bike wire with m flash red wire and then turn signal main gray wire with m flash black wire but i got no electrical signal at all. I then went with my old flash relay and connected wires as they used to be, again, no luck, no electrical signal at all. I don't know what's going on. What is wrong !

[AndyH]

Did you check the fuse(s)?

[aminemed]

Yes, changed the fuse for a new one...very weird :s :s

no lights at all in the bike. Engine turns over when i hit the starter, but can't get an ignition. I guess that keeping on trying will drain the battery.

[Bodi]

Probably the surge made a dodgy connection or switch contact fail. You need to follow voltage through the harness and find where it stops. Corrosion and wear take a toll on connectors and switches.

[aminemed]

Is a multimeter ok for that ? To follow voltage ?

[Mr. Mike]

Yes a multimeter is exactly what you need, along with the electrical print for the bike.
And a good stroke of luck to find your point of trouble.

Although your first post is not the original, the end is the same. Dig into this forum on "how to check a selenium rectifier".

[aminemed]

Let's suppose i was able to find out the failed contact, how can i fix it ?

And by the way, now that i did this big mistake, what should be the wiring of the M FLASH according to the instructions ?

Gray (turn signal main) with black and +12V black wire with M FLASH red ?

Thank you

[aminemed]

Please help ! I bought a multimeter but don't know what to do exactly...what a mess ! Can't believe that this wrong wiring is causing all that

[calj737]

Aside from adding the M-Flash, is the rest of your bike stock?

[aminemed]

Stock except for the combined rectifier/regulator i've installed

[calj737]

That's what I did. After my mistake, i connected the black +12v bike wire with m flash red wire and then turn signal main gray wire with m flash black wire but i got no electrical signal at all.

This is still wrong. The BLACK and the GREY both carry 12v in your stock harness.

M-Flash RED to BLK/Grey wired together.
M-Flash BLACK straight to Ground.

Before you do this, remove the old flasher relay. Confirm with a meter that your new fuse has continuity across it. Check the battery voltage too. If both those are good, turn the key to ON, and check voltage on both sides of the fuse. Still good? Got any lights at all on the bike?

If so, proceed to the engine coils. Check voltage at the BLK/WHT wire to make sure the KILL/RUN switch is passing voltage still. If all these things are good, start the bike. If not, post where it stops passing these tests.

[540nova]

Calj737 will sort you out. Be confident in what he says, he's the Motogadget guru.

Sent from my SM-G955U using Tapatalk

[calj737]

Calj737 will sort you out. Be confident in what he says, he's the Motogadget guru.

Not true. But I will try hard to steer you correctly. 

[aminemed]

I will run all these tests when i get back home. But just for my knowledge, can a wrong polarity damage a battery ? I mean in my old flash relay (picture), i was plugging the black wire and the gray wire at the same time. Didn't have room for green ground wire. Thanks for your explanations

[calj737]

Your old flasher is a 2prong and the light fixtures themselves had the ground. BLACK brought power to the flasher from the key, GREY carried it to the switch. Switch passed it to BLUE or ORANGE, etc...

With that M-Flash, it needs to sit in between BLACK and GREY because BLK brings the power to the flasher, GREY onto the switch... You’ll have to tie RED/BLK /GREY together, then tie M-Flash BLK to ground. That should basically “replicate” the stock circuit with a newer flasher type.

You can damage a battery by reversing polarity, but not by doing so with that flasher. Jumper cables, sure, but not your “accident”. More likely you’ve damaged a switch or connection somewhere, OR, cooked the fuse block and you don’t realize it.

[aminemed]

Ok so i run through tests:

battery = ok ! 13 volts +

fuse continuity = ok

voltage across fuse box = ok

Turned key on, still no lights.

checked black & white going to engine coils = ok, showing same voltage as battery.

Still no start of engine. As said before, can hear it turning over, but no ignition.

Then what i did is tested both black and gray wires that i plugged in the M Flash, so black = ok (voltage = battery), but gray wire is not giving any good output. Guess it might be the issue. How can i be sure and how can i fix it eventually ? Thank you

[Bodi]

Inexplicably, I thought about this while driving home just now.
Nothing you could do by connecting any flasher to just black and gray could possibly cause the issues you are describing. Either you're leaving some things out of the story, or the failure happening just when you connected the M-Flash is a coincidence.
That assumes the harness hasn't been ravaged by a PO or has damage that cross connects wires.

Depending on what lamps you have in the signals, reversing the connection might damage the M-flash module if you try the signals that way.

And yes, the M-flash module should connect with red-black and black-gray. But stop worrying about it: it isn't the problem, and didn't cause the problem.

[calj737]

Inexplicably, I thought about this while driving home just now.
Nothing you could do by connecting any flasher to just black and gray could possibly cause the issues you are describing. Either you're leaving some things out of the story, or the failure happening just when you connected the M-Flash is a coincidence.
That assumes the harness hasn't been ravaged by a PO or has damage that cross connects wires.

Depending on what lamps you have in the signals, reversing the connection might damage the M-flash module if you try the signals that way.

And yes, the M-flash module should connect with red-black and black-gray. But stop worrying about it: it isn't the problem, and didn't cause the problem.

The only damage he could have caused on the bike is blowing the fuse, and possibly the flasher. But otherwise, I agree wholeheartedly that he could not have damaged the “bike” further.

[aminemed]

yes very weird then. I remember that before installing the m flash I turned the key to on and tested my lights, all ok. Then replaced the old flasher with the m flash and turned key on and total black out, you know the story. By the way when looking at the diagram I think that gray wire if not connected to a flasher would show no voltage at all so that's why my gray wire was nit displaying anything on the meter

And just to be sure on how to measure with the meter (we never know) meter black with battery black and meter red with the wire to be tested, right ?

Lastly, can I check my headlight lamp for example with my battery to see if I have lights, maybe all my lamps are gone

[calj737]

Meter black to any ground
Meter red to voltage (20vdc range please)

You can check the white wire in the headlight bucket/socket for voltage with key ON and headlight switched ON. Blue wire if on HI beam