New Member - 82 SX400

Hey yall,

So this is my first motorcycle, and I'm super stoked about it. I'm still trying to nail down what model it is, and from what I've read, I've so far figured that it's a DOHC. Can anyone give me anything more specific?

VIN: JYA12R00XCA005784

Only problem is, wiring is not my strong suit, and the wiring on this bike is incomprehensible to me. There are wires everywhere, and some of them go nowhere!

Everything seems to work so far, except no high beams (no clue where to start with that), but I'd rather not start cutting wires out until I'm sure they aren't necessary. It just seems like an awful lot of wires for a few lights and an ignition system, but I'm sure they were put there for a reason. I've searched the forums and read up on it, but I understand most of the wiring diagrams about as much as I do the situation on the bike right now.

I did however find this diagram a member posted in 2012, and It's actually readable and I can follow it. Question is, is it sound? If I follow this diagram, and cut out all the extra stuff, should everything work properly?

Thanks in advance for the help!

There are many wiring diagrams on here for each different sub model. You need to determine your bike sub model which you can do based on VIN. Also post pic of bike and someone will verify. .

After all that, is it just your high beam that isn't working? It so then that really narrows down the wires you'll be looking at! And you can search accordingly for thread discussing high beam issues. Can't imagine you're the first

Here are some photos of the bike, as well as the wiring. I searched the forums but didn't find much on either subject. Is there a guide on how to break down the VIN?

All I found on the high beam issue was something about a yellow wire. There is a yellow wire coming from the plug that plugs into the light, but the yellow wire that it was plugged into goes to a plug that does't plug into anything. Maybe you can make sense of the photo, maybe not. I guess I should also mention that neither of the brake switches activate the brake light.


In the photo below:

1. Comes from the brake lever, so I'm assuming that's the brake light switch. Not connected to anything, and no matching male plug.
2. The yellow wires that were connected. Probable have something to do with the high beams. As you can see, the other end goes right into one of the plugs shown in 3.
3. Two weathered plugs, neither of which plug into anything. No matching plugs.
4. This wire wasn't plugged into anything, and I don't know what the other end goes to either.
5. These two wires were soldered together.. No idea why, or what the other ends go to.
Unmarked: See the blue wire coming from the big white plug. That has been spliced into, sending the red and white wire to an extra wire coming from the headlight. It will not turn on without those wires connected.

Model info: http://www.xs400.com/threads/history-of-the-yamaha-xs400.4458/
year should be on vin plate on steering column?

Might have mentioned it but the first thing I'd do is check the bulb.

That wiring diagram is meant for a SOHC bike but would mostly be the same.
It's also mostly complete. You'd be better off using the stock wiring diagram in the DOHC manual.

Your bike is a Maxim, which I don't think we have a manual for, but the wiring info in the Seca manual will be the same.

Thanks guys. Figured out that the rear brake light switch needs to be replaced. Front brake light switch is getting replaced too, and i figured out what wires it connects to. Thanks for helping me ID my bike as well. That helps. Still unable to resolve the high beam issue. The previous owner had installed an aftermarket LED headlight unit, which may be part of the problem. I don't plan on riding much at night anyway, especially not out of town, so I'm about to the point of just putting it back together and living without high beams for now.

I had a similar problem with my 82' Seca (also DOHC), where ONLY the brights would work. The headlead actually has two filaments, one that is always on (low beams) and another that turns on/off with the high beam switch, turns out the connector had melted at some point and prevented solid connection of the low filament. I had to cut away the melted plastic to get a solid connection. Maybe check the bulb by directly connecting it to the battery or look at the connector for the bulb?

*EDIT: Sorry, just saw that it's an LED bulb, the conector still might be a problem