Topic: M-Unit not properly turning off headlight - Please help!

[TheWiredNinja]

Okay guys, I have a weird issue with my headlight and I have searched to no avail...

When key is turned to 'on' my '72 CB750 headlight turns on and functions normally, as do all the other lights and functions with the m-unit and momentary switches.  However, when I try to manually shut off the headlight by holding the button down for over 3 seconds, the lights on the m-unit indicate the 'light' has shut off, but in fact, the headlight remains on.  I can select high beam and the m-unit indicator light switches from 'light' to 'high' and back to normal 'light' indicating correct function and of the switch.

I have even tried to set the control manually via the options menu so that you'd have to press the momentary switch for the headlight in order to turn on.  It still comes on when the key is switched on, despite the m-unit indicating it should be off.

Blue Wire is coming from 'high' straight to the headlight and a white wire from the 'light' to the headlight with the black from headlight to a solid ground. 

Here's the kicker - when accessing the menu of the m-unit, it properly shuts off the light!!  It cycles through shutting it off and on when rebooting.  This should mean that it is an m-unit issue and not my wiring and is properly setup.  What in the hell is going on here?  PLEASE someone help me out.  I am using an old school halogen non-replaceable headlight (60w) if that matters? 

further side note - The high beam indicator is always on (blue wire) to my Gauges indicating that there is power being sent, despite the m-unit saying it's off.  I'm so confused. 

[calj737]

Couple of questions:
M-unit or Bluetooth enabled?
Not running the m-button, correct? Straight wired to m-unit?

You can run a single wire from LO to headlight LO if the bulb is a single filament and use only the buttons to toggle between HI/LO

[TheWiredNinja]

This is the Bluetooth enabled version.
I am not using the m-button - all wired directly to m-unit.

I also apologize for my wiring nomenclature.  I have directly wired from the m-unit output what is labeled "headlight" (red wire) directly to my headlight.  The blue wire is coming from "hbeam" directly to the headlight the unit as well.

Just so that I understand, you want me to run a single wire (red wire in my case) from the output "headlight" and see if the Hi and Low beam still work?  (it is a dual filament lamp that has a high beam function which does work when I tap my headlight button)

Further note:  The high beam indicator on my chronoclassic gauge does indicate the highbeam is on, regardless of situation.  I'm thinking this may be a clue that indicates 12v is coming from the m-unit when it is not supposed to.  But then again, my high beam flashes when I want it to... so this is mind boggling to me.

[calj737]

This is the Bluetooth enabled version.

And you are configuring the unit via your mobile phone?

Just so that I understand, you want me to run a single wire (red wire in my case) from the output "headlight" and see if the Hi and Low beam still work?  (it is a dual filament lamp that has a high beam function which does work when I tap my headlight button)

Correct. See your manual, section 8.9. A single wire out from HI to headlamp. A single push of the LH control will toggle between HI/LO.

Further note:  The high beam indicator on my chronoclassic gauge does indicate the highbeam is on, regardless of situation.  I'm thinking this may be a clue that indicates 12v is coming from the m-unit when it is not supposed to.  But then again, my high beam flashes when I want it to... so this is mind boggling to me.

This is an indication that your HI wire is energized not by the HI condition. Do you know/recall exactly what wire you tapped into to feed the gauge for HI? It should be the HI wire from m-unit. But leave it as is for the moment, and remove the LO output wire. And try your LH button for toggling.

[TheWiredNinja]

Firstly, I'd just like to say thank you for trying to help me out - I really appreciate you in trying to solve this!

I have configured it on the m-unit itself using the horn button.  I end the configuration by holding down the horn button and letting the m-unit 'reset' (which cycles the headlight on and off btw)

I will try your recommendation of using a single wire from the 'high beam' of the lamp to the pin where the red cable (regular beam) was located.  I do see the diagram in the booklet, and this is an interesting bit of news as I have yet to try this setup.

Yes, I do know that I tapped the HI wire by the blue wire, which was connected by the 'Hi beam' on the m-unit.  I basically tied the 'hibeam' (blue cable) directly with another smaller gauge cable into the proper location leading into my chronoclassic (12v+ input).  If I disconnect that very cable from the input of the chronoclassic, the light goes out. 

[TheWiredNinja]

Okay, so I couldn't wait and despite having a few beers in me, it WORKED!  (well sort of)

Having a single wire did not entirely work as all it did was energize the bulb when it was in indicating "Hi" on the m-unit causing the bulb to work as if it were a energized regularly (aka. not in high beam mode) then shut off completely if I were to use the 'LO' mode. 

Strangely, it is sort of working when I then added the 'LO' wire into the 'Headlight' output at this point while the ignition was still on.  I now have LO beam operational, along with HI beam when I press the button!  The gauge indicator even works properly.  HOWEVER, if want to activate the HI beam permanently without having me to press the button (ie. hold the button for 2 seconds), it seems to default to a LO beam output, even though it says 'HI' is activated.  lol, do you follow me?  It's confusing as hell and I don't know why this is happening to me, but this is the best outcome so far. 

It seems there is some sort of weird gremlin within the m-unit as to how it's detecting the input/output and acting accordingly.  So a big THANK YOU for accidently working this out even though I am still dumbfounded as to what the hell is going on.  I can live without the option for a HI beam permanent option (holding headlight button for 2 seconds) if everything else works as it should.

[calj737]

I will try your recommendation of using a single wire from the 'high beam' of the lamp to the pin where the red cable (regular beam) was located.  I do see the diagram in the booklet, and this is an interesting bit of news as I have yet to try this setup.

The two outputs (HI/LO) can work with a push button, but in actual fact they are designed for switched position controls. every m-unit I have ever configured or wired (in the hundreds now) I use a single BRAKE/TAIL wire and a single HI wire. Worked every time.