Topic: CB550 M-Unit Wiring Schematic

[shads]

I was hoping you fine gentlemen could possibly give my wiring diagram a quick go over to check I haven't seriously messed anything up!  Pretty much everything is new components apart from the stock handlebar controls.  Ive read through a lot of posts on here and all the manuals and I think (hope) everything is correct, but would be great to have someone more experienced have a look.

A couple of points/questions:

 - My bar end indicators have a white and yellow circuit, so im using the white for running lights which are turned off when the indicator on that side is on, via the function in the original controls.
- The horn switch ground through handlebars doesn't work as ive got powdercoating and clips on, so rather than scratch through everything im running a separate new ground wire which will attach to one of the inside screws to provide ground.
- Im trying to find some striped wire that I can use to replace some of the doubled up colours.
- Anyone got any ideas for what I can use for the ground block in the headlight?  I seem to have a lot of ground connections.
- What thickness wire should I use for the ground connection between the ground block and the frame connection at the coils?
- Do the three yellow connections from the stator to RR have any particular order?  Im assuming they don't.
- Am I right in thinking that the yellow and blue wires to the points are connected to the ground terminals of the coils?

Thanks very much in advance! 

The PDF is full resolution by the way.

[540nova]

This is how I brought all my grounds from the handle bar switches to a central location.  There are actually more grounds than this. I collected many grounds into molex connectors, in the headlight bucket,  such as 4 in, ganged together, on a 4 wire plug,  with one output wire to this ground bus.

Sent from my SM-G955U using Tapatalk

[shads]

A couple of points/questions:
- The horn switch ground through handlebars doesn't work as ive got powdercoating and clips on, so rather than scratch through everything im running a separate new ground wire which will attach to one of the inside screws to provide ground. Skip the ground block, and move all your grounds to the main frame behind the steering neck. This eliminates any current running through the neck bearings.

Ok, ill change it to that, thanks.  However there is no ground going through the neck bearings as the current wiring collects all the grounds in the headlight bucket and then connects them to the frame ground at the coils with one wire.

Every switch on your stock handlebar controls with the exception of KILL/RUN, needs to have its wiring routed to ground. Every input on the left side of the M-unit (except LOCK) is a ground trigger. Do not route power to the left side.


Yep, I currently do have every left side input connected to ground, including KILL.  Im using KILL/RUN to switch ground to the KILL input.  I dont have any power to the left side except LOCK, have I missed something?

- Anyone got any ideas for what I can use for the ground block in the headlight?  I seem to have a lot of ground connections. See above
- What thickness wire should I use for the ground connection between the ground block and the frame connection at the coils? Since all the stock controls only need to signal a ground to the M-Unit, you can actually use as small as 24AWG from frame to control to M-Unit. I used 22AWG specifically.
- Do the three yellow connections from the stator to RR have any particular order?  Im assuming they don't. Correct, they do not.
- Am I right in thinking that the yellow and blue wires to the points are connected to the ground terminals of the coils? Yes. BLK/WHT from KILL/RUN provides 12v (or IGN from M-Unit) depending upon how you wire it.  Yeah my +12v for the coils is coming directly from the M-Unit IGNITION out (brown wire)

[shads]

This is how I brought all my grounds from the handle bar switches to a central location.  There are actually more grounds than this. I collected many grounds into molex connectors, in the headlight bucket,  such as 4 in, ganged together, on a 4 wire plug,  with one output wire to this ground bus.

Sent from my SM-G955U using Tapatalk

Ah, using a molex plug!  Thats a great idea, thanks!  I like the earth bus bar too

[shads]

Looking at your gauge, the RPM input needs to come from either BLUE or YELLOW from the coils, not a 12v signal from IGN.

I did wonder about this as it seemed a bit odd to take it from the +12V side.  But the instructions do show the RPM input connecting to +12V...

Are you disabling the KILL/RUN switch function by tying it to GROUND? It should be IGN->KILL->RUN->12v@Coils. This enables the handlebar to interrupt the power to the coils in an emergency. No ground termination needed.
Yeah I was wiring it up as per the manual.  But I prefer your method so ill change it to be an interrupt switch

url picture

[shads]

You’re misreading the tach signal. It’s not coming from the M-unit IGN, it’s coming off the coil Yellow wire. This is the signal from the points plate, not providing “power” as the IGN port does.

What that signal is looking for is the firing speed of the coil, and the M-unit IGN port only shows 12v constantly when the key is activated. The Yellow wire from the coil/points cycles with the motor speed, firing the plugs as the motor turns. That’s the info the gauge wants.

Make sense?

Gotcha.  Makes perfect sense, thanks again

[shads]

Updated diagram.  Thanks for the help guys 

[shads]

Hi Cal, my understanding of the OEM indicator switch is it has two function.  One function CLOSES one of the circuits when moved (ie the grey, blue/brown and orange wires) and the other one OPENS a separate circuit when moved (ie white/brown, white/orange and white/blue wires).  In my diagram (copied from the one from the manual), the left contacts are the CLOSE circuit and the right contacts are the OPEN circuit.  The two circuits are independent as far as I have tested and as per what the switch connections show on the diagram.

Im using the CLOSE circuit to provide ground to the indicator left and right inputs of the M-Unit (via the orange and light blue wires), and also using the OPEN circuit to provide power to the white lights on the front indicators (via the white/orange and white/blue wires).  This means that the white indicator lights are ON when the main headlight light is activated, but switched off when that indicator is activated by the control switch. 

No power hits the M-Unit as far as I can see.  Im very happy to be wrong though!! 

[BomberMann650]

Must have been working on the yamaha too much.  Seeing red go to turn sigs tripped me up. 

[shads]

Hi Cal, thanks again for the input.  Let me just say that I really value your opinion and you are one of the legends of this forum.  Maybe im being dumb here but im struggling to follow the issues you raise.

- I actually used that Gordo schematic to make mine.  Mine is functionally almost identical to that one as far as I can see, however I wanted to show every wire and connection (including ground wires and where they terminate) which is why mine looks a lot more busy.  When I compare both, the Gordo one has 6 'power' wires outputting from the M-Unit to the components at the front of the bike whereas I have one more wire due to the M-Unit Blue also having an IGN output.  Both diagrams have 6 'trigger' control wires sending ground from the front of the bike to the M-Unit inputs.  There is very little difference between the two, other than I have some different components such as a tacho/speedo with more features, M-lock, and im using the white lights on the indicators as running lights.

- The additional work to make my indicator white lights work with the headlight is simply connecting three wires that will already be there, no additional wiring or work is needed.  As im using the OEM switches and wires from the switches to the headlight bucket, all I need to do is connect the white/brown from the indicator switch to the white LIGHT wire that in the headlight bucket (powering the headlight itself) and then connect the white/orange and white/blue from the OEM switch to the indicators.  All these wires will be in the headlight bucket whether I used them for this feature or not.  How would I make this indicator feature work without putting current through the indicator control switch?  Looking at the OEM diagram it looks like this is what the secondary circuit of the indicator switch was designed to do (ie interrupt a white running light on the indicators when that indicator is on), so im struggling to see the issue here.

- The only power going through the indicator control switch is for the two white LEDs on the indicators, which draw very little current.  The wires on the LED are minuscule.  There is no headlight current going through any switch, the headlight is directly connect to the M-Unit LIGHT output!

- Also, power does hit a switch in the Gordo one - the Kill Switch.  Why is putting very low power through the second circuit of the indicator switch any different?

Not trying to be confrontational here, just trying to understand where ive gone wrong! 

[shads]

Sorry, im not referring to the setup of the orange indicator flash rate, I mean the secondary white lights that my indicators (and the stock setup) have.  These indicators have TWO sets of lights each, one orange LED for the turn signal and one white LED which is used as running lights that are ON when the headlight is ON, but momentarily switch OFF when the indicator is functional...  That's what im doing with the additional wiring, in using the stock controls to switch the indicator WHITE running lights off when the flashing indicator ORANGE light is on.

I think this is where the confusion is coming in!!