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Headlight Wires?

Chuck CT125

New member
Joined
Jun 16, 2021
Messages
2
Good to know. I'm only using it to charge my phone or GoPro so don't know if that will be an issue. RPMs will be fairly high most of the time which should be enough to keep them charged. I'll keep an eye on it and come up with a plan B if necessary.
Hi - Just got my US 125 and was looking to hook up my USB to the headlight wires today. Any guidance? 323-337-5094
 

op46

Active member
Joined
Feb 2, 2021
Messages
168
Location
a ridge overlooking Lake Guntersville, AL.
If you want it switched so it is only hot when the key is on use the black with yellow wire in main bundle as the positive and the green wire in either of the turn signal wire bundles. The darker blue posi-taps worked great. My wires are a little larger than the Honda ones. If you want it hot all the time take it to the battery and put on the positive and negative or something that is a direct off them.CT125switchedDIN.jpg
 
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TrailBoss

Administrator
Staff member
Joined
Oct 11, 2020
Messages
298
Location
Pennsylvania, USA
So I got this all sorted out. It was indeed the yellow/white wire that needed to be tapped to trigger my fog light relay when high beam is engaged. I can't explain it, but measuring with a multimeter gives incorrect results. Eventually I had an epiphany and tested things out and it works great.

So to summarize, I now have a set of fog lights installed that turn on with the high beam. Nice and simple.
 

FRAC

Member
Joined
Jan 25, 2021
Messages
59
TrailBoss, I've attached a scanned file of that section of the wiring diagram from the Service Manual. I'm sorry, but may have told you wrong. If you look at the bottom 'dimmer switch' section it shows white for low and yellow/white for high. However, at the 'headlight' section on the left it shows white for high and white/yellow for low. I'm truly sorry for causing confusion with bad info.
Would you mind posting the a picture of the right side of the wiring diagram? My manual did not come with this.
 

Fun4me

Active member
Joined
Apr 20, 2021
Messages
154
Location
O'Fallon, Illinois
Would you mind posting the a picture of the right side of the wiring diagram? My manual did not come with this.
The wiring diagram is a fold out so the scan is in three files. You can print out, overlap, and tape them together
 

Attachments

  • scanCT 125-1.pdf
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  • scanCT 125-2.pdf
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  • scanCT 125-3.pdf
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timmmy todd

Member
Joined
Jan 15, 2021
Messages
51
leave every thing together use pointy probe for voltage test at back of plug.at headlight plug junction. tin positive wire . stick in back of plug .same place as probe. if you feel snug fit tape her up. that is how I did it 1600 miles no problem
 

Dead sailor

New member
Joined
Jul 2, 2022
Messages
2
So I got this all sorted out. It was indeed the yellow/white wire that needed to be tapped to trigger my fog light relay when high beam is engaged. I can't explain it, but measuring with a multimeter gives incorrect results. Eventually I had an epiphany and tested things out and it works great.

So to summarize, I now have a set of fog lights installed that turn on with the high beam. Nice and simple.
Howdy. Im having troubles doing the same. I have it grounded and tied into the yellow/white wire, but nothing happens. ??
 

Timmy6216

Member
Joined
Jul 15, 2022
Messages
93
Location
Eastern Nc
I am very interested in where this goes. I have been known to upgrade ALL lighting on MOST of my motorized things.,, I'm talking about LED in tail housing, head lights fog lights....etc..

I don't care about halo rigs and such. I want lumens darn it . in the even ill wire switches as I see fit, but it would be sweet of I could use existing wires.
 

TrailBoss

Administrator
Staff member
Joined
Oct 11, 2020
Messages
298
Location
Pennsylvania, USA
I gave up. Wired straight to battery with an inline fuse and a switch. Works great!
I'll take that as a no? If so, the only thing I can say is perhaps the voltage coming off the signal wire was not sufficient to run the lights. This is why you use a relay, since you're only using the signal wire to "trigger" the relay to then direct connect the battery to the lights. It's the safer way to go. If you direct-wired to the battery then you're fine, but you definitely don't want to direct power anything big from a signal wire.
 

Harv

Member
Joined
Jul 14, 2022
Messages
48
Location
Memphis
The wiring diagram is a fold out so the scan is in three files. You can print out, overlap, and tape them together
These PDFs need to be pinned to the top of Tech Discussion where the Manual is. These are pure gold. Great job Fun4me!
 

JTB

Member
Joined
May 23, 2022
Messages
27
Location
Washington
The issue people may be having with triggering a relay to power aux lights with the high beam (white/yellow) is that the high beam runs on 7.2 volts).

IMG_0603.jpeg
For many 12v automotive relays a trigger voltage between 6-8 volts will not operate the relay's coil reliably (or at all in many cases). My solution was to use a 6 volt automotive relay(used on some 50 yr old cars). These are very rare and impossible to find at an auto parts store but fortunately they can be had from Amazon for $10.

 

Motoboogie

New member
Joined
Jun 17, 2022
Messages
27
Location
Indy
Gents, all a relay does is protect the switch from too much current.

Depending on the amp draw or switch, a relay may not be needed. Normally, it’s better to be on the safe side and use a relay.

In saying so, anyone have a link where I find a small 12 volt relay?
 

Harv

Member
Joined
Jul 14, 2022
Messages
48
Location
Memphis
The one that APPEARS to do what is needed is the white wire. It changes voltage based on the high beam switch. HOWEVER, the problem seems to be that even in the low beam position, the white wire is still putting out about 8v, and that's enough to trip my relay and turn on the lights. With high beam on it puts out 14.4v, which trips it as well, as expected.

For many 12v automotive relays a trigger voltage between 6-8 volts will not operate the relay's coil reliably (or at all in many cases).


Having issues wiring up my lights. The RIGIDs are rated at 9-15V. I get why the 8-8.5 volts on a lot of the wires won't trigger. However, the white wire does jump to 14.5v when high beams are on so why won't that trip the aux lights on? I have good current from the taps and ground. I can turn on either amber backlights or white fog lights with a 9v battery. I cannot get the lights to come on with bike voltage, either with 5-pin relay or direct taps to the white wire (on high beam) and ground. I couldn't find a 5-pin 6v relay so I guess I'm stuck with trying two 6v 4-pin relays.

Any thoughts would be greatly appreciated.
 

JTB

Member
Joined
May 23, 2022
Messages
27
Location
Washington
Having issues wiring up my lights. The RIGIDs are rated at 9-15V. I get why the 8-8.5 volts on a lot of the wires won't trigger. However, the white wire does jump to 14.5v when high beams are on so why won't that trip the aux lights on? I have good current from the taps and ground. I can turn on either amber backlights or white fog lights with a 9v battery. I cannot get the lights to come on with bike voltage, either with 5-pin relay or direct taps to the white wire (on high beam) and ground. I couldn't find a 5-pin 6v relay so I guess I'm stuck with trying two 6v 4-pin relays.

Any thoughts would be greatly appreciated.

Harv,
Sounds like a few different issues here. First, it seems like you are trying to use the "white wire" to trigger a 12v relay and I don't expect that to work as you intend if the voltage doesn't drop sub 6v(it should really be sub 2v to work reliably) when the high beams are off(allowing the relay to switch off). I again suggest the HB(white/yellow) wire and a 6v relay. The relay I linked to above IS a 5 pin relay.

Second issue, LEDs are Light Emitting Diodes and diodes are devices that only allow current to flow in one direction. So unlike old timey incandescent lights, the polarity (+/-) must be correct. The voltage fed to at least some of the headlight wires is NEG compared to ground (not POS as you may expect). I have not tested the white wire but this is true of the HB(yellow/white). If this is also true of the white then you will need to reverse the polarity of the wires (ground is now +) to power them directly on the white wire.

Third, it is less common, but some types of relays will not trigger if the polarity of the trigger wires are not correct. Again, at least some of the headlights are powered NEG compared to GND. So if you are using the NEG signal to trigger a relay it may only work if the polarity of the trigger wires are reversed. The 6v relay I posted a link to does not care about polarity.

Sounds like you have a multimeter so you can easily test if the voltage you are getting is NEG or POS on the white wire.
 
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Harv

Member
Joined
Jul 14, 2022
Messages
48
Location
Memphis
Thanks JTB. Have ordered the 6v.

I clicked on that link before I knew anything about relays so didn't even know about 4 vs 5-pin at the time. I spent 4 hours messing with it today and just couldn't get in my head how 14.5 volts measured with the red lead + on the white wire and black - on the ground wire would not power my lights. Even without the relay involved, tapping directly into the white for power and green for ground did nothing. I tried tapping the white/yellow wire initially but when I measured 8.5v on it I went searching for something over 9v which lead me to the white wire on HB. Touch those same aux light wires to 9v battery and it lights right up.

Everything I saw regarding relays said that 85 and 86 pins were interchangeable, didn't matter. Thrown in the NEG trigger factor plus one way polarity and my mind just melted down. I'll try swapping 85 and 86 (and back to the white/yellow wire) while I'm waiting for the 6v to get here (due Wednesday). Thanks again.
 
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