I'm working on the wiring of the indicators on my '72 Honda CB750. I don't have the manual and I've also had a really tough time finding the manual online (I've found a '73 but there seems to have been some pretty significant changes between '72 and '73 in regards to the electronics).

I've taken some pictures that I've posted below to hopefully get some clarity. If you all have an answer that's great but I also understand that there is a degree of troubleshooting I may need to do so even just getting pointed in the right direction in regards to how to test all of this would be great. I have a multimeter and other electronics tools if there is any use for those.

Before I get into the pictures, the thought I'm having is that I most likely need to:

• Connect the wires coming from the main light to the indicator 'controller' (into the controller; am I right in assuming these are the right wires to power this?).

• Connect the indicator light itself to the out current from the controller.

I imagine it's that simple, I'm just have trouble identifying which wire is a ground wire, and where the current is coming from, etc. etc.

Thanks so much for any help, I'm just diving into this thing headfirst so any advice is greatly appreciated. Thanks!

Here are the pictures:

The light with indicators that I've installed (not yet wired)

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The light works when I flip the switch. There are two wires coming out of the light with connectors. I'm assuming these will power the turn signals? There is an orange and a green wire. This link: http://www.cruisercustomizing.com/guides/motorcycle-lighting-and-electric-guide indicates Green = Ground, Orange = Left Turn Signal, Light Blue = Right Turn Signal. Am I missing a wire?

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This is the actual indicator switch which I took apart to investigate the wiring. Obviously the red and green control the different sides but I'm not sure about yellow and black.


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And here are the ends of those wires:

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Finally, I have the light itself. The light itself has a black wire and black wire with a white stripe:

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1 Answer 1


I think you have a problem

The photo's of your harness and various components are not OEM. The wires are too new looking, as well, your turn indicator relay is definitely aftermarket.

Here is what a stock 1972 CB750 turn signal relay looks like.

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As well, your headlight bucket is matte black. I worked in Honda dealership working on these bikes and can't recall a matte black (plastic?) headlight bucket existing on those models. I could be wrong depending on geography, they have made one that is matte black. If it's plastic though, it's not OEM.

Your new wires do not look OEM either.

You may just have to unwind the changes that the previous owner made OR reverse engineer the components to discover what circuit they belong on. A multimeter and a test lead to give batter power to your relay would be the place to start and work your way out from there regarding finding continuity.

  • Thanks! This is all great information, I'm still learning of course. I believe the light itself was installed by the previous owner. Would that imply that the there would be different amounts of current etc for that light? Is there not a standard current (may be the wrong terminology)? I'm definitely wanting to try to restore everything I can to OEM and it looks like those flasher relays are on Ebay (ebay.com/itm/like/…; looks like maybe you got your picture from this). Oct 11, 2016 at 21:46
  • If anything, I'll start going down the road of undoing what they did and getting the bike back to it's OEM parts. Thanks for the help, this is great! Oct 11, 2016 at 21:47
  • It should ALL be 12.6 volts. You shouldn't have to worry about that. Verify by checking your battery. If it has 6 cells, it's 12 volts. Oct 11, 2016 at 21:52

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