Motogadget M-Unit Installation on a Honda Shadow VLX

For my first ever adventure into wiring a motorcycle I decided to install a Motogadget M-Unit into my 2004 Honda 600 VLX.  It isn’t a glamorous bike, but its mine. Over the next few months I will continue on with other more noticeable changes, but since its my only bike, and I would prefer not to have it down for weeks or months at a time, these changes will be done piecemeal.

Because of this approach, it became clear that the first thing that needed to be done was upgrading the electrical system to accommodate new lighting and controls. The M-unit offered a very elegant and simple way of doing this, which to me, a total novice, seemed well worth the $300 price.

There are some forums dedicated to the 600VLX,but  it seems very few owners are interested in doing the kind of changes I want, or at least none that post. What posts I could find about wiring were pretty simple – The most complex issue was dealing with installing LED turn signals on the harness which wasn’t designed to accommodate them. All this meant that to install the M-Unit, I was pretty much going to have to figure it out on my own.

The M-Unit is designed to simplify wiring and can, apparently, work very when building an entire harness from scratch. However, going all the way to scratch was beyond the scope of what I thought I wanted to do (In retrospect, having accomplished what I have and learned as much as I have, I will start from scratch next time.)

What I’m going to attempt here is to break down, piece by piece, how to integrate an M-Unit in the a Honda 600VLX wiring harness,  keeping all the functionality of the original system, while adding the functions of the M-unit and removing the bulky and ugly stock controls. For simplicity sake, I’m going to use the OEM wiring diagram as reference and simply work my way around it, clockwise, item by item, and explain what to do with it. After which, I will discuss the new wiring added for the M-Unit and new controls.

NOTE: When I say “Cut and Cap” I’m saying a wire is not needed, and can be removed. If you want to open up the wiring harness and removed all the excess wires, like I did, do this carefully. Several wires branch off to multiple items. When removing a particular wire from a particular item, trace it back to the main wire of the same color where you’ll find the soldered splice. Do not cut the main wire, only remove the spliced on piece you don’t need any more.

My understanding is that many Hondas of this type have very similar harnesses, so a lot of this should translate. I hope you find this helpful.  Here we go!

Mounting the M-Unit: Under the seat, there is a black metal brace, on which is mounted a black cube – The Turn Signal Relay, which isn’t needed any more, so getrid of the relay, and mounted the M-Unit to the metal bracket, by drilling two holes in it. Easy.

At the top end of the Unit, I attached a ground wire and grounded it to the frame with a self-tapping screw (I think the metal plate could have served as a ground, but I felt a wire to the frame was more certain).

The M-Unit mounted and grounded where the turn-signal relay used to be.

THE OEM HARNESS

Ignition Switch (Key): Three wires: Red leads to the M-Unit Positive power input screw on the lower right. Red/black goes to the M-unit LOCK input (I soldered this wire to a smaller gauge wire to plug into the M-unit). Cut and cap the Blue/Orange wire, you won’t need it.

REAR LIGHTS (Tail, brake, turn signals and license plate): Disconnect all these connectors. If you want to reuse the nylon OEM connectors, cut the wires a few inches on the main harness side to attach to later. If you’re going to install new connectors or simple wire directly to the existing wires, cut them on the non-harness side of the connector.

Cut the three wires leading into the tail/brake light connector (Green, Brown, and Green/Yellow), a couple inches on the main harness side of the connector. Splice them all together into a single wire, and attach it to the M-Unit BRAKE output.

When programming the M-unit, set it for a single-wire brake system (LED or light bulb, which ever you have) and the tail/brake lights are all set.

Rear Brake Switch: Both brake switches are wired together with a Green/yellow wire. From the connector there is a black wire that goes to ground, leave it. Follow the Green/Yellow wire to where it leads to the tail/brake light connector (which you probably already cut), before it reaches the tail/brake light connector, cut it and plug it into the M-Unit BRAKE input.

Basically, what you’re doing here is placing the M-unit between the brake switches and the brake lights, by cutting the Green/Yellow wire and attaching switch end to the input and the lights end to the output.

Fuse box:  Remove the box and toss it, you don’t need it anymore. Four wires lead out from the connector: The Black, Black/brown and Blue/Black wires all attach to the M-Unit AUX output (which is a solid state fuse box) by soldering them all to a single wire. The Black/Red wire is cut and capped, its not needed anymore.

Main Fuse/Starter Solenoid: Four wires. The Red wire connects to the M-Unit at the Positive Power input screw, along with the Red wire from the Key Ignition. The Yellow/Red wire plugs into the M-unit START output. The other two, (Red/White and Green/Red) stay as is, leading to the Regulator/Rectifier.

Regulator/Rectifier, Alternator, Ignition Pulse Generator, Ignition Control Module: Leave these.

Turn Signal Relay: You removed this when you installed the M-Unit. Cut and cap all three wires. DON’T wire them to each other, cap them off individually.

LEFT HANDLE BAR CONTROLS:  The plan is to lose the whole bulky button housing. The only two wires to keep are the Green/White and Green Red wires, which connect to the clutch switch.  Everything else gets cut and capped (Drk Blue, Blue/white, Green, Orange, gray, Lt Blue, Black and Black/Brown).

NOTE:  If you choose to remove the clutch wires too, all that happens is you can’t start the bike with just the clutch pulled, the gear box will have to be in neutral.

Dimmer Switch: This feeds low power to the turn signals, so they are also marker lights. I plan on switching to 2-wire LEDs anyway, so I discarded this all together.

NOTE: The M-unit does have a programmable setting to fill this feature, however, the way I choose to wire, that program did not work. In my case, the OEM turn signals function only as turn signals.

Front Turn Signals: Disconnect both. Just like with the rear, if you’re going to reuse the connectors, leave yourself a few inches of wire to connect to, then cut and cap the remaining wires.

NOTE: I think, but I’m not sure, that if you solder the solid colored wires and the color/white wires from each turn signal together, creating a single wire, the marker light feature of the M-unit will function. But I have not tested this, since I really don’t care.

Headlight: The M-unit will now handle this. Cut the Blue and White wires a few inches back from the bulb connector. Attach new wires to each and run them to the M-unit, White to the LIGHT LO, and Blue to LIGHT HI. Green is your ground, you can leave it.

Indicator lights (Turn signal, Neutral and High-beam dash lights):  The single turn signal light and High-Beam indicator light will be powered through the M-Unit, so cut those wires a few inches back from the connector on the main harness side, and cap the remaining wires. Leave the Green and Lt Green/Blue wires.

Gauge Lights (Meter light, Temp Indicator, Oil Pressure): Leave these.

RIGHT HANDLE BAR CONTROLS: Even though we’re losing the bulky Starter/Engine Stop box, we need some of these connections. The Brown wire needs to be connected to one of the Black/brown wires. Do this either by keeping the other side of the connector where a small loop of Brown/Black wire makes the connection, or by cutting and splice the two wires together. The Black and Black/white wires need to be spliced together. If both of these loops are not made, the bike won’t start.

Cut and cap the Blue/White, Black/Red, Yellow/ Red. Keep the Green/Yellow and other Black/Brown wires (these are your front brake switch wires).

Side Stand Switch, Diode, Fan Motor Switch, Temp Unit, TP Sensor: Keep. The Diode, in case you’re wondering, is actually just a connector with a black cube plugged into it and wrapped in tape inside the wiring harness, if you don’t open up the OEM harness, you won’t even see it.

Horn: There isn’t a nylon connector here, just two black wires that plug into two tabs on the horn. The M-unit will control the horn, so you’ll need to connect one of these to the HORN output (by cutting and extending it) and the other to ground. One of the black wires does connect to a green wire if you follow it, that is the ground - leave it connected. Cut and extend the other wire to plug into the HORN output of the M-unit.

Neutral switch/Oil Pressure Switch: Leave these wires.

Ok, that’s it for the OEM harness. The M-Unit should come on when the key is turned and do its little LED cycle, ending with the LOCK and AUX LEDs lit. If you attach a temporary button to the START input and to a ground, the bike should start up. You should be able to also turn the head light on and off, and switch between high and low beams, using the same button at the LIGHT input. Same for the horn and each of the turn signals (but you might need to configure some things first.)

Connect a temporary button to the CONFIG input on the M-unit, and to ground, and follow the instructions to program the M-Unit for “one wire brake lights.” Once that’s done, the brake lights should work from both the front and rear brakes individually.

If all that works for you, you’re in great shape!

Now onto installing new control switches. I opted for the 5-button setup with the M-unit. The buttons are headlight, right and left turn signals on the left, and horn and start on the right (thanks to the M-unit, a double tap on the start button will kills the engine.)

THE M-UNIT CONTROLS HARNESS

All the buttons I used with the M-Unit are “Momentary” buttons, meaning they only close the circuit while being pushed, as soon as you release them, they spring back to the open state. The M-unit can also be programmed to work with “Japanese and European” buttons setups, which is what you’d use if you kept the stock controls (but why would you? They’re so ugly!)

All buttons have two wires, one which leads to the M-Unit, and one which goes to ground. You can ground your wires however you like, and you can connect all your grounds together to reduce clutter/confusion and save space. The M-Unit uses very little power for the buttons, so you can use very thin wires (I used 22 AWG).

Start Button: Run a ground, and plug the other wire into the START input on the M-Unit.

Horn: Just like the Start Button, a ground and one wire plugged into the HORN input.

Headlights: Same as above, input into the LIGHTS input (see a pattern here?)

Turn Signals: Again, one wire to ground for each button, and one wire each to the M-Unit inputs, TURN L and TURN R.

That’s its you’re buttons are wired. Seriously, look at the OEM wiring diagram to accomplish what you just did, its insane how complex it is without the M-unit!

M- UNIT LIGHTING HARNESS

This is a bit more complicated, but if you take it step by step, its pretty easy.

Headlight and High-Beam Indicator:  Splice into the Blue Headlight Wire, and connect it where the Blue wire was at the Indicator lights harness. Where the Green wire was on that harness, should be connected to ground. Now when you turn on your high-beams, you’re indicator light will come on too.

Turn Signals: This is the complicated one, so take it one step at a time. Both left and right are identical, so just repeat the procedure.

Top: The stock headlight and turn signal controls. Bottom: New Motone Mini-Buttons, much smaller, cleaner look, plus Blitwell Kung-Fu grips. .

A wire needs to leave the M-Unit from the TURN L or TURN R output and split into three wires. One will go to the front turn signal connector, and one to the back and one will be bridged to the indicator light on the dash.

 The second single wire from each of the connectors needs to go to ground from each signal itself.

Once this is done, the turn signals should work. To make the dash indicator work, attach a 1N4001 Diode to the third wire from each of the turn signal harnesses.  Be sure the direction of flow for the diode is away from the M-Unit.

 Then connect the other end of both diodes to a single wire which will connect the either the Lt Blue or Orange wire from the Indicator Lights connector. The other unused wire should go to ground. Now the indicator light should work when the turn signals come on.

That’s it! You should now have everything on the bike working. Program which ever features you want for the M-Unit.

Fully wired M-Unit. 

If you’re leaving your bike otherwise stock, there’s probably not a lot of point in doing all this. But, if you’re planning on future mods which will impact the electrical system, everything should be pretty simple now, just plug into the existing wiring and, if necessary, change the programming of the M-Unit to accommodate the new item.

Any new accessories (hand warmers, ground effect LEDs, etc) get spliced into the AUX power lines. Changes to the lighting just plug into the connectors you already have.

I hope this was helpful!

UPDATE: One the second day after finishing, I took my bike out for a night ride and immediately noticed that all the lights were brighter. The headlight, which I had planned on upgrading, is suddenly perfectly adequate, the turn signals are brighter and the dash indicator lights are actually annoyingly bright!

I'm not sure exactly where, but its clear that somewhere this new setup is saving a lot of juice which it can now devote to the lights.