Yamaha XS400 Wiring Diagrams

[Bury Me In Smoke]

To compliment my last post, here are the wire colors from the ignitor unit. As you can see, there are no solid black, solid gray, or solid orange wires here. For my application I’m going to try to match the wiring colors to those coming out of the ignitor unit since this will be a point of reference for future troubleshooting. The diagram shows solid brown, solid white, and solid green wires as an intermediary harness. I think that’s an opportunity to improve and save myself future frustration.

 

[anthony nunes]

Is that your plug coming from a rectifier is there a way to test those rectifiers I’m having a charging problem now with my 1980 XS400

 

[Bury Me In Smoke]

Is that your plug coming from a rectifier is there a way to test those rectifiers I’m having a charging problem now with my 1980 XS400

It’s the plug for the ignitor unit. It’s the brains of the ignition system.

 

[Liamthedevastator]

Going to contribute to this thread with a ledger sized and coloured 1977 XS400D Wiring Diagram.

 

[Dav-len]

Hi all
I am looking for xs400 1980 wire diagram.
The 1981 says there is a head light relay.
Yet mine does not seem to have one. I’m confused. Can any one assist?

 

[xschris]

80 models has them at the front of the bike next to the neck under the gas tank.

 

[Dav-len]

That means some one took mine out and rewired the bike, talk about a pain lol. No worries will sort her out thank you for the information. I will be adding photos soon as I start assembling her.

 

[dannyTheBoat]

This is a simplified wiring diagram the PO gave me with the bike. I verified it when I had to do work on the fuses. It says its for an '81 xs650 but it works with my '82 xs400 as well, granted the only stock electronics left on my xs is the ignition module. Just the bare bones basics. I've had the bike for close to 3 months now and I've put probably about 300 miles on it with no electrical problems except the occasional battery drain when left sitting. This might be a good resource for someone doing a compete rebuild and wants a basic circuit to get the bike on the road, or something along those lines.

 

[Spitfire_X24]

In my quest to build my own wiring harness from scratch for my '78, I decided to translate the awesome ones on the German XS400.net site. I'll post the translated versions here if it's ok. Hopefully they will help anyone looking to do this. I also modified the one to include the three position light on/off/hi/lo switch included in on of the addendum's to the original drawings.

 

[Ernestoman]

Haven't seen much on the 1981 XS400H wiring diagram. Is it the same as the XS400SH? Trying to rewire this thing but I have no idea where to start

Edit: After a little digging, I found a thread on another site saying "The XS400 H (Special 2), SH & SJ (Heritage) US models share the same harness", so I'm guessing the wiring diagrams are probably the same

 

[CaptChrome]

@Ernestoman, yes, the H and SH have the same wiring. The diagram for the bikes are part of the factory service manual available for download at the top of this forum.

 

[Ernestoman]

$20 well spent on ebay

 

[ace_of_spades]

Wow that's for sure!

 

[Ooolers]

Hi, I am trying to put together (finish) a sx400 -86 project scrambler bike that i just bought.
And part of it is get the electric together.
And there is one thing in the electrical wiring diagram that i cant find in a lot of other diagrams. What does the Black and white wire (cirkeled in the image) connect to? And what function does it have? It is connected to one of the pins in the contact that plugs in to the TCI, but where should it go from there?
Also a picture of the bike in progress.

 

[tstidham]

Is it maybe a tachometer signal wire? I don't know enough about the late model 400's, but did they switch to an electronic tachometer or is it still a cable driven mechanical tachometer?

 

[Ooolers]

It is a mechanical tachometer, only mechanical wire from the engine and front wheel, but i don’t have the actual tachometer so I can’t check how it looks in the instrument cluster.

 

[CaptChrome]

Nice looking rear sub-frame on that bike. You made it so that it does not look like an after-thought!

I don't know a lot about the DOHC bikes, but the factory wiring diagrams are pretty good, so I expect that the B/W wire is not supposed to be connected to anything. Sometimes parts are used on a few different models or are designed for future ideas, should the bike model prove successful and make it to the upgrade stage. As @tstidham said, it could be a tach signal output which this particular bike does not use, but might come in handy if Yamaha was thinking of moving to electronic gages for its models (they were, but the XS400 did not survive into that era).

 

[Ooolers]

Thanks @CaptChrome but i can’t take credit for the sub-frame that was the previous owner. But i think it looks great to.
Then I will wire everything in and see if it works

 

[Ooolers]

Hi, I am trying to put together (finish) a sx400 -86 project scrambler bike that i just bought.
And part of it is get the electric together.
And there is one thing in the electrical wiring diagram that i cant find in a lot of other diagrams. What does the Black and white wire (cirkeled in the image) connect to? And what function does it have? It is connected to one of the pins in the contact that plugs in to the TCI, but where should it go from there?
Also a picture of the bike in progress.
View attachment 38872

I think i have found a clue in the diagram for a sx650, there the B/W wire goes to a side stand switch.