Topic: Where do these wires go? Headlight not working

[BakedPotato65]

Hello I have a 74 CB750 that I inherited. The first owner had a fairing on the bike so the headlight and front turn signals were missing when I got it. There was a wiring harness that seemed to just unplug and unsplice from a few wires in the headlight housing so not too big of a wiring mess. I’ve got a new headlight and front turn signals, so far I’ve got the turn signals to blink. However the front signals don’t glow when the bike is running, I don’t know where the negative signal wire goes on the front blinkers, I don’t see any place to plug them in.

Then when I plug in the headlight to the original three print plug, the headlight does not even turn on. All wires look intact in the housing. Then there are two mysterious white and blue male wires sticking out of one of the main harnesses. I’ve looked at diagrams and have no idea where they go. There is also a red female wire coming out of the starter solenoid that I don’t know where it plugs into and also an unplugged green female wire just above the starter solenoid but part of a different harness. Both under the seat area. I’ve tested resistance between the unplugged female wire under the seat and the green ground plug on the headlight harness, these two are connected. So this wire is part of my problem of no headlight. It’s hard to describe so hopefully the pictures will help.

Thanks a lot

*The bright red wires in the pictures are the new positive turn signal wires*
t


Sent from my iPhone using Tapatalk

[Mr. Mike]

Congratulations on the inheritance!
Looking at the electrical diagram for your model, on this site, dark blue goes to the high beam, white to the low beam and another dark blue (same as high beam) runs up from the headlight bucket to the high beam indicator lamp.

The red wire according to the diagram looks to come off of the start relay + side then over to the top of the fuse block 15amp circuit.

That green wire is frame ground.

Look again at the wiring diagram provided here on the site as it shows what your looking for.

Just an observation here, but it looks like there are two black wires connected to two greens in the headlight bucket. I cannot find this connection on the diagram.

Check out the diagram to verify what I’m seeing. Color for color

[my name is nobody]

two blacks hooked to greens would cause a dead short (if those are original wires)
Green=ground
Black= is key on power
white=low beam
dk. blue=high beam
your plug for the bulb looks wired correctly. Check the metal taabs inside of the plug for good contact
between them and the headlight bulb. not uncommon for them to be loose and no contact.
don't worry about those two wires, red and green by the start sol., as they aren't used.
Front lights have running lights (dual contact 2 filament bulbs, 1157) two wires coming out of them.
one side (left) is org/whit stripe and one solid orange. the other side (right)has Lt /blu solid and Lt blu /whit stripe.
see if that helps any... the headlite plug harness terminals, white wire has single female end, ground (green)has single male end, and dk blue has dual receptical female terminal on the end of single dk blu wire.
some of your wiring obviously isn't completely stock(?). that fat looking white wire for the headlite(?). do you have 2 wire sockets for running/
sig lites? If not. its probly why the lights don't "glo when the bike is running"...check headlight fuse
and make sure the fuse box clips are clean and tight, and no evidence of the fuse holder melting also.
On stock FRONT turn sigs, the ground is through the signal housing. Those big nuts inside the headlight
housing with wires attached that plug into the main harness complete the circuit. sounds hard, but it really a matter of matching/connecting wires of the same color. Someone please correct any misinformation/mistakes if I have given any in this post.

[Scott S]

 You should also do something about the bare wires on the Yellow/Red and Brown/White.

 If the 750 wiring is anything like the 550 (and it probably is), both of those have to do with the ignition circuit. The Y/R comes from the start button on the RH control and goes to the starter solenoid. The Br/W comes from the ignition switch. I believe it is how power is routed to the LH control so that you have power to the turn signal switch, Hi-Lo, etc.

[BakedPotato65]

Problem solved. A combination of all of your suggestions helped fixed it. The main problem with the headlight was that the white and blue wires were switched out. I unplugged the white and blue that were in it and then plugged the other white and blue wires and it lit up. The signals work now and so do the running amber lights in the front. Thank you so much for all the help


Sent from my iPhone using Tapatalk