No headlight, errant brown wire and 11 volt

Windmill John

Windmill John

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Location
East Sussex, England
Different bits in the title, but 11 volts on brown wire is possibly bothering me more than headlight.
Right, clarity… Just wanted to check electrics, connected battery, all other lights and horn good.
Headlight not working. No feed to wires feeding headlight plug. I’ll be checking left hand switch gear.
But whilst staring in the bowl, I noticed a loose brown wire. Tested it and giving 11 volts with ignition on and black test lead to earth.
During the rebuild, I had cleaned all the contacts I could find. The brown wire is slightly thinner gauge than the browns in the white block it goes to.

I’m going to settle down with a circuit diagram, but in the meantime, on the off chance 🙄😊 hoping someone might shed light on the wire.
11 volts, I’m guessing voltage drop. Battery across terminals is giving 12.3 volts; I will charge later, but that’s enough for testing.
Battery positive to engine block still gives 12.3 volts. Is there some secret earth point hiding…
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IMG_0341.jpeg
 
The brown in the headlight bucket is just a spare. Brown = running lights. In some jurisdictions they were required to be “always on” and they’d run through that circuit - same as the taillight.

11 volts is mildly concerning. What’s the thru-switch output in the white and blue to the headlight?
 
Obviously I’m in the UK, but the front indicators are on with ignition; American import I’m happy to leave as is.
I need to get into the handlebar switch. There is no power to the white or blue at the bulb contacts.

The only browns I could see in the Clymer was CDI; we’ll ignore that. And parking light. Rear light did come on in the ‘P’ position; not sure if headlight side should come on but it didn’t.

Yes, 11 volts… I checked a couple of contacts in the headlight bucket with black lead to earth and got from 10.8 to 11 volts.
Luckily I closed my eyes and blocked it from my memory 🙄
 
The headlight brown wire is a switched off the ignition switch spare as Pete noted. You have an issue with something causing that low reading, as you should be getting close to battery voltage on all circuits. Start by probing other 12VDC circuits for a voltage spec. Check the taillight and the power to the coils etc.

Check your main ground cable from the battery to the frame area and make sure you have a good ground to start with off the battery.
 
Thanks to you both.
As part of the ‘getting it running’, I did:
Removed and cleaned up main earth connector to frame.
Removed whole back end to clean and paint mudguards, which involved disconnecting all wires there, cleaning.
Coils were removed to access valves and this gave me the opportunity to clean the earth contacts there.

Next time I’m in the shed, I’ll go through all connectors again, probing voltage and checking.
Maybe when I check the ‘L/H’ switch in the bars I’ll discover something.
When I was in the headlamp shell the first time, I disconnected all connections, lubed and cleaned.

Yes, I want my 1 volt back!
 
Windmill John said:
Obviously I’m in the UK, but the front indicators are on with ignition; American import I’m happy to leave as is.
I need to get into the handlebar switch. There is no power to the white or blue at the bulb contacts.

The only browns I could see in the Clymer was CDI; we’ll ignore that. And parking light. Rear light did come on in the ‘P’ position; not sure if headlight side should come on but it didn’t.

Yes, 11 volts… I checked a couple of contacts in the headlight bucket with black lead to earth and got from 10.8 to 11 volts.
Luckily I closed my eyes and blocked it from my memory 🙄
Click to expand...
More than likely bad grounds (unless the battery is just undercharged) - just as an FYI - there's a separate brown circuit from the ignition switch that runs straight back to the taillight (red oval), your dead-end end brown is the blue circle.1781717866863.png

That switch connector on all of my CX's and GL's (basically same exact wiring layout) was an issue.
 
Thanks Pete. I did search for a colour diagram for mine, but no go. I did, in 2021 whilst furloughed, colour in a black and white CX500 wiring diagram. It’s still on the CX site.
 
Assuming this machine is wired "lights on", all the time, power from the electric starter switch is fed to the dimmer switch via the brown/white wire. When the start button is pushed, the lights go out and power is shunted to the starter relay (yellow/red) to crank the engine.
 
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Okay, I’m afraid a little confused here.
12 volts both sides of headlight fuse.
I did a continuity test from the three wires in the handlebar light switch and got continuity to the three other ends in the headlight shell.
Just as an aside, I connected power from battery straight to the blue connector then the white connector on the headlight and headlight lit both low and high; that was using the earth from the headlight.
I’m still in the shed looking into it, but not sure where next.
 
Sorry Pete, won’t be able to check until tomorrow afternoon. I’ll fill in here once done.
I’m not scared of electrics, just struggle with them!
Looking at the wiring diagram, I guess as the yellow/black at the handlebars comes from the fuse, I should get 12 volts between that and earth.
Then that leaves via either the blue or white to the headlight and I should get 12 volts on either depending on switch position.
 
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