wire harness rebuild--newbie intro-- and a question

aaroncarver

aaroncarver

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Hey there. I'm Aaron Carver. Motorcycle newbie. Yamahaclub newbie. Milwaukee Native and resident. Proud owner of a 1979 Yamaha xs400. I used to ride a Honda Ruckus--A fun bike with not enough pep. Thanks to everyone for all the information on this great site. I've left some posts elsewhere on this site but I didn't know about forum etiquette so here I am to introduce myself properly...and ask a question

I'm fixing up a 1979 yamaha xs400 and the first place I started was the wiring. I pulled off the tape of the wiring harness and discovered that it had "modified" by the previous owner. Many circuits were crossed and there were insulation cracks and bad splices etc. So I figured I'd return the bike to stock condition--which meant completely rebuilding the harness. So I clipped all the plugs and taped them to my kitchen table in the order they appear on the wiring diagram in my manual. Then I threw away all the old wiring. Then I spent three days memorizing the wiring diagram.

Yesterday I spent 14 hours wiring circuit by circuit, plug by plug, component by component. It was a daunting and mind bending task, but when 12:30 am rolled around I had finished everything but the Ground, which I measured and cut and labeled ahead of time. (I chose to wait till the end to install the Ground because of the way the ground attaches to every circuit--It would have made following the wiring diagram much much harder.)

Everything went smoothly, albeit excruciatingly methodical and plodding. I need to adjust some of the wiring lengths, but that shouldn't be a problem. I only have one problem and I hope someone here can be of aid. The headlight cutout relay has a yellow wire with a red stripe that travels to a Fuse. From the other end of that Fuse, the yellow/red wire travels to the right handlebar switch (electric start button and kill switch) assembly, where it fits into a clip. BUT there the wire dead-ends. JUST STOPS. And according to the wiring diagram that is exactly how it is "supposed" to be.

It seems that it should've gone to the electric start button, but it most certainly does not. Can anybody explain this to me? Can somebody look in their right handlebar plug and tell me if their yellow/red wiring is attached to anything at all?

I'm truly stumped.

Aaron
 
Hi Aaron
From the diagrams I looked at for the 1979 models, the yellow/red wire goes to the turn signal switch and I believe its part of the self canceling system. Does your right handlebar switch have an on/off switch for lights? One possibility that comes to mind is that you have a mix of parts and the right handle bar switch is from a 1978 model.

Which wiring diagram are you using as a reference?

The 1980 and 81 models have a lighting relay module that turns the bike on after the bike starts.

Harvey
 
Hey there. Perhaps I should've been more specific. This is the diagram I used: http://www.xs400.com/forum/showthread.php?t=4466
It's identical to the one in my manual, but some kind soul took the effort to color it.

There is a yellow/red going from the turn signal cancel unit, but the yellow/red I'm talking about it goes from the headlight canceler unit to a fuse. From that fuse comes a wire that goes to the kill switch/e-start assembly. This is where it gets tricky: Observe the kill switch/electric start assembly in the diagram posted above.

According to the diagram there are 4 wires coming to this kill switch/e-start assembly clip from the harness: 3 white/reds, 1 blue/white. But only three wires leave that clip and actually go the kill switch/e-start assembly

Now, according to my bike, one (of the three) red/white wires is actually a red/yellow, and this yellow/red is the wire that dead-ends in the clip. does that help explain my question?:confused: this stuff is hard to describe in words...
 
Hi Aaron,
I looked at your picture. went back to the wiring diagram, and saw the relay you are talking about. Its in the lower left hand corner of the diagram? Its not labeled, but I'm going to assume its the headlight relay switch, which trips when motor starts, turns on the headlight. Trace the L/B back to the left handlebar switch.

After looking at your picture I'm thinking the yellow/red that goes to the right switch should be red/white, part of the electric start system.
 
well...yes. that is the headlight cutout. The diagram I used is the color diagram posted by Jayel in the thread I posted. According to Drewpy in another of my threads, the headlight "cutout" relay cuts out the headlight while bike is starting so it doesn't drain the battery.

But I'm not talking about the the L/B wire at all. And I'm not referring to the left handlebar switches either. I'm absolutely specifically only talking about the the YELOW/RED WIRE THAT GOES FROM THE HEADLIGHT CUTOUT RELAY and eventually ends up at the ELECTRIC STARt/KILL SWITCH ASSEMBLY HARNESS CLIP and DEAD-ENDS THERE.

I rephrase it Again:doh: the yellow/red wire travels from the headlight CUTout relay to a ten amp fuse, and then goes directly to the electric start/kill switch harness clip AND STOPS. This makes it appear that the yellow/red wire does nothin. edit: AND it appears that the ten amp fuse in question does nothin--because the wire that is coming off it dead ends in a harness clip


I'm not suggesting this is wired incorrectly--I'm not an electrician or a motorcycle guru. I'm just curious to know if someone else would disconnect their electric start/kill switch harness clip and tell me if the yellow/red wire is actually is connected to anything in that clip.
 
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I understand your frustration. What I believe is that from the right hand starter switch to the plug the red/white wire is powered by the yellow/red wire (or maybe the other way around, after thinking on it) that comes from the fuse box. Thats my best shot. Hopefully someone else can come up with a better take on it.
 
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ahale2772 said:
dose it look like a factory dead end or a cut wire?...might be a model change thing?
Click to expand...

Well, it's a dead end. The wire goes into the harness clip, but the start switch/kill switch assembly half of the clip has no connection for it. Like I mentioned above. PLUS :banghead::banghead::banghead: I've already noted that this set up is recorded in the factory wiring diagram.
 
Hi Aaron,
Been thinking about this on and off during the day, hate unsolved puzzles. Took a look at the wiring diagram from the German site when I got home from work. Their right hand switch has an on/off position for the lights, using the y/r wire. No light relay though. Also, looking at the fuse box connections, the 3 10 amp fuses all share the same brown power connection coming from the ignition switch, even though that doesn't appear on the wiring diagram you used. That would seem to explain the need to keep the fuse, otherwise you may not have lights.

Anybody else have any opinions?
 
hmusket.

Muy interesante. I'm going to study the german diagram and get back to you. **It** sounds like you're on to something. I too hate unsolved questions.
thx
 
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does your right side switch assembly have a headlight on/off switch? my 78 does, but i already tore the wiring harnedd out and i'm at school. i'll look into it when i get home today.

BTW sorry for the necro, i forgot i was looking through old threads.
 
I'm necro-ing this thread because no one ever really gave a definitive answer.
I removed mine (XS400F) and she still runs fine (also removed the yellow line and the ground from the headlamp relay to the generator)
 
Im sleepy reading this thread so forgive me if i got this wrong. The run switch wire does just end because its ground is the handle bar.The wire goes into the housing attaches to a plate.

When the start button is pushed in it touches the plate and complets the ground throught the handle bar. Vola the the current flows throught the solinoid and sparks fly.

I read over your post again and my answer is right. :)
 
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