Honda CX 500 Forum banner
1 - 3 of 3 Posts

18 Posts
Discussion Starter · #1 ·
I've spent the past couple days doing a ton of research about the wiring on my '82 GL500. I've decided to make a custom wiring harness mostly from scratch, as I plan to relocate/delete a lot of components for a cafe build. My main goal is to simplify the harness, and keep the bare necessities as I don't want a rats nest under my seat. I plan to reuse stock connectors for the components I'm keeping, which is the Ign switch, start button, ignition system, and charging system. I'm planning to run my starter, headlight, brake light circuit myself, using appropriate relays/solenoids/wire size, etc.

While everything I plan to do is pretty straight forward, I want to confirm my understanding of the rectifier and ignitor chip wiring. I am aware that the 3 output wires for the rectifier are: Green=ground ; Red=to battery, black=voltage regulator reference. As far as the 5 ignitor chip wires go: green=ground, yellow & blue=input signals, black/white=power, then another blue and yellow (i think) as output signals to coils.

This was a little confusing to me at first, but I'm pretty confident I have everything right. The only thing I'm not sure of is where I can run the black voltage regulator reference wire to. It seems to go all over the place in the stock harness, but from my understanding I'm assuming I can just run it to the battery along with the red and white wire. Could I just connect the 2 together straight out of the regulator? I'd say I'm pretty familiar with general wiring, but I've never really played with stator and rectifier wiring before.

Any help or advice is very much appreciated!!

Attached is the wiring diagram I've been using along with looking at my deloomed wiring harness from the bike.
Also attached is a general idea of what I plan to do with the harness I plan to make.
OG Wiring Diagram

simplified diagram


Super Moderator
5,340 Posts
Welcome to the forum.
Looking at your diagram I don't see a temperature gauge. A temperature gauge, or at least an idiot light, is a vital gauge on a water cooled bike. It is easy to destroy one of these engines by unnoticed overheating.

Super Moderator
'84 CX650E that is evolving into a GL500
17,743 Posts
Welcome to the forum. Please add your location and your bike's model and model year to your profile so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).

And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and the Previous Owners may or may not have done the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).

The best advice anyone can give you about customizing any vehicle is to get it safe & reliable in more or less original condition and use it for a while before you start making any changes so it can tell you what changes it needs to make it do what you want/need better. That approach almost always results in something you actually want to keep and use but making changes based on style or on what someone else (who may or may not really understand how the changes affect the way it works) has done often results in a piece of expensive yard art that you can't stand sitting on for more than a few minutes and might even be dangerous.

That is a terrible copy of the wiring drawing; It is small and fuzzy and doesn't even say which model it is for (there are some small differences between the '81 and '82 and between the Interstate and naked models). The '82 GL500 Interstate drawing below (from the CX Wiki) is much better (& we are working on replacing the drawings there with more accurate versions soon - note that the diode is connected backwards and there may be other small errors).

And for the generic minimalist drawing you posted what amounts to a thumbnail. Here's the full size version. That would get a bike working but it is far from adequate.

It is very easy to "simplify" the wiring by removing circuits but it is very poor practice to render the bike unsuitable for use on public roads in the process:

The temperature gauge Mike mentioned is very important (several cases have been reported on this forum of engines being destroyed by overheating on bikes that didn't have working temp gauges).
It is a legal requirement in the US and Canada to maintain all lighting functions that were on the vehicle when it left the factory and for your GL500 that includes turn signals, front running (marker) lights and brake light switches on BOTH brake systems (front & rear).
Note that the turn signals must be 100mm/4" from any other light that is on when the signal is flashing (this is a good law because if they are closer it is hard to tell if it is actually flashing); Honda were very clever and used front signals with dual filament bulbs for markers & signals and the turn signal switch cuts power to the marker when you turn the signal on. (FWIW, I have separate markers and signals on my bikes with tiny but bright 1W LEDs that you barely notice when not lit on the CX and somewhat larger LED lights on a bar mounted to the GoldWing's lower triple clamp; Since they are more than 4" from the signals they don't need to turn off when the signals are on, which allowed me to replace the ancient & very tired original switches with ones from a model that doesn't have that feature).
That drawing doesn't even include a horn (yes, that is required too).

BTW: If you are going to mess with the wiring I also recommend downloading the Honda Wire Color Codes chart from the Wiki and making every effort to use the same colours Honda used whenever possible to make future troubleshooting easier.
1 - 3 of 3 Posts