Topic: How To: Install aftermarket wire harness CB750K

[DaveI]

After chasing continuity and plugging and playing for days, and also with a lot of help from HondaMan, heres the photo installation to get the $75 aftermarket wire harness to actually work with your bike:

Step one: CHECK the harness!  Make sure everything is solid and secure before the installation

Step two: CHECK all of your block connectors and clean as necessary

Step two: Disconnect your battery and remove the old harness but do not throw it away.  It can come in handy when trying to see what's wrong if you have issues and all those male and female bullet connectors may be required.

Step three: Lay out the new harness and wrap it with a 1/2 inch loom for addd protection (about $5 at any local hardware store). 

Step four: Install the new harness but don't secure it down yet.  My preference was to start at the back of the bike and work my way forward.  The harness should run on the inside of the frame (between the battery and the frame) and all of the connections should reach their respective parts.  It should also be very neat at this point.

Step five: Run the harness up the frame to the front of the bike.  There are may ways to do this but if you go by the Honda shop manual, you should be running it on the underside of the middle frame rail and above the ignition coils.
From there it should go out the left hand side, above the gas tank mount (theres a little indent) and though the forks.
*Note: you may have to remove the ignition coils briefly to run the harness.

Step six: Go inside, get a beer and the ole' soldering iron out or butt splices and make some 3-4inch long male-to-male jumper cables.  I couldn't find the right size male connectors locally, so I cut some old cables, soldered them up and gave them a fancy electrical tape wrap.

[DaveI]

If you don't want to solder the connections, be sure to use weather-proof butt splices and make sure they are secure

[DaveI]

Step seven: You need to use a continuity tester or multi-meter with the continuity function for this.  The new harness will have two brown/red female connectors in the wire harness, a single black female connector and a single brown female connector in the headlight bucket.  None of these were here before but it's very important that you install these correctly.

Using your newly created jumper cable, connect the single black female connector to the single brown female connector.
This is what will give you a running tail light!

[DaveI]

Step Eight:  This is where you need to check the continuity.  As mentioned, there are two brown/red female connectors in the bucket now.  In the OEM harness, there is a connection from the brown/white wire (headlight control switch) to the brown/red (headlight power) underneath the loom.  This is no longer the case.
Take the continuity tester and take put one side to ONE of the brown/red cables.  Put the other side to the back-left, brown/red wire (pin) fuse box pin connector.  If you do not have continuity, switch to the other brown/red female connector in the headlight bucket.  When you have continuity between the female and the correct wire in the fuse box you have found the connection we are looking for.

[DaveI]

Step nine: take your other newly fashioned jumper cable and connect the single female brown/white connector in the headlight bucket to the brown/red female connector in the headlight bucket that has continuity to the pin in the fuse holder we just located

[DaveI]

Step ten:  For a sanity check and to make sure you did steps eight and nine properly, take your continuity tester and check the other brown/red female connector in the headlight bucket and check for continuity to the front left (brown/red) pin in the fuse box pin connector:
*side note: you're checking it to the block in the wire harness, not the actual fuse box

[DaveI]

Step Eleven:  you have continuity?  Good!  Take the brown/red wire running from your left hand control switch and plug it into that brown/red female connector.

Step Twelve: Switch your headlight and tail light fuses.  The 5amp tail light fuse should go where the 7amp was (center on the 1974) and the 7amp fuse should go where the 5amp fuse was (bottom clip)

[DaveI]

Step thirteen:  Plug everything else in where it should be (match the colors) and zip tie the harness down or use the clamps if you have them
*make sure you don't squeeze the harness when securing it down.  The zip ties should be just tight enough to hold it without crushing it.

Step fourteen:  Re-connect your battery and give it a try.

[CycleRanger]

What aftermarket harness and for what year bike does this information apply to?

I installed a harness from Parts-N-More in my K5 that didn't require any special jumpers.
Everything wired up and worked fine stock.

It's PN #24-4001 and it's listed for CB750K 73-75.

[DaveI]

This harness was from CB750supply.  Its on my 1974 K4 which I am pretty sure uses the same harness. (73-75 on the site).

I think the harness is an EMGO as HondaMan made a post about the black wire that got me to where I needed to be.

[lucky]

I used that 1975 harness on my 1978 and it was plug and play on almost the whole deal. Only a couple small glitches and I did not modify the harness .

Instead I just got a different handlebar switch.

[DaveI]

Maybe the it's the stock swith gear then. When I tried it without the jumper cables I fashioned I had no power to the headlight or tail light.
When this worked plug and play for everyone else did you have any connectors that weren't used or did something plug into every single one of them?

[CycleRanger]

Maybe the it's the stock switch gear then. When I tried it without the jumper cables I fashioned I had no power to the headlight or tail light.
When this worked plug and play for everyone else did you have any connectors that weren't used or did something plug into every single one of them?

For my K5 the harness matched the diagram exactly. Colors were all correct.
The only extra wires were the one in the headlight for the Euro parking light and the extra green ground at the blinker relay.

Are your switches stock?

[Ravie]

Ok, I understand this is a SUPER old thread...  but earlier today forum user edwardmorris (Yay Raf!) sent me a link to this and IT WORKED. So other guys using this really stupid EMGO harness...try this out. It will work!

And I don't know if the guy that wrote this is still around on the forum but...dude...you rock.