XS400 electrical issues


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Flint, MI
I'm having a few issues that I'm having trouble figuring out.
I put the bike back together this week. Battery was dead (going to buy a new one), but I gave it a charge and started it up after some struggling. Got the bike running, but here are where the issues start.

Previous owner threw the electrics together pretty sloppy. I haven't had to touch them until now. When I started up the bike, I had power to my headlight and tail light, but my brake light, blinkers, and dummy lights weren't working. I took it for a ride today, hit my kill switch, and it's now 100% dead. No lights, won't start, even with a jump. Pressing the start button or kicking it does nothing.

Now I don't think it's the kill switch. Everything seems to be OK there, and I can short the starter to get it to turn over. I checked the connection with a multimeter and it seems okay.

Kick starting the bike will not work, neither will push starting, or shorting the electric starter. It turns over but it's not catching.

Electrics on this bike are daunting to me. I've slowly been checking connections but I'm not making much progress. Any ideas?

Get a new battery and clean the contacts on your handlebar switches and fuse box. The battery needs to maintain a relatively high charge to be useful. Get a volt meter too, very useful tool.
I've replaced the battery, cleaned connections on handlebar switches and checked everything in the fuse box. Still nothing.
Stock fuse box with glass fuses?
Use a voltmeter to check continuity from fuse holder to fuse holder. Not across the fuse itself.
You can have a good fuse in a bad fuse holder and get no continuity.
They can still look decent but have enough surface corrosion to cause problems.
Or install an aftermarket blade style fuse holder.

Barring that, work your way from the battery, up to the ignition, back to the fuse box, measuring for ~12V to ground at each point that any connection happens.
At some point you'll read battery voltage on one side of something, and no voltage on the other side, and you'll have found your problem.
After some digging, it looks like the previous owner completely bypassed the fuse box. He's got a 4 inline fuses down near the ignition unit. None of them are blown though.

The ignition plug in the headlight assembly (leading toward the battery) isn't reading any voltage, but the battery reads just fine.

I'll do some digging tomorrow and see if I find anything.
I've found one bad fuse holder for a brown wire. Replacing this fixed the dummy lights, turn signals, horn, and tail light. Headlight does not work, brake light doesn't turn on.

There is power to the ignition, but still no start.

Both kill switch wires have continuity to the fuses shown on the diagram I'm looking at, and the blue start button wire has continuity to the starter.
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There is a headlight relay. Shouldn't turn on with the bike off.
Don't waste time on it until the bike is running.

Previous owner's hack job makes it hard to say.
Keep tracing voltage.
Check all the grounds. Starter switch grounds through the handlebars.
Maybe revert back to stock fuse wiring if possible. At least then it would match the diagrams.
That's the thing, when I short the starter it would usually turn the headlight on.

I'll definitely be putting in a new fuse box to make this easier.
I'll clarify. The headlight relay activates when the motor is spinning.
When you short the starter I hope your motor is spinning.
Problem is mostly fixed now.

New battery, new fuses and fuse holders, cleaned and resoldered connections to the solenoid. It runs now. Headlight is still out, but that'll be an easy fix.

Reason it wasn't starting after these fixes was because I connected the ignition coils backwards. Must have happened when I was checking voltage. I guess we all make stupid mistakes sometimes :)