Baffled??? Headlight issues. (Warning!! Technical)

Normally electronics are my thing, but this one has me stumped.
Never had an electrical issue with my Seca before, and this one just showed up out of nowhere.
I went to start the bike for a nice evening ride, started fine, ran fine, but no headlight.
Everything else is perfect. it all works.
Pulled out the headlight relay, bench tested it, works fine.
Now here is the catch..... I pulled the metal cover off the relay, pressed the switch side down to close the contact and the headlight comes on just like it should.

So in to the wiring.
There are 4 wires. Black, white/blue, blue/black, and red/yellow.
The black and white/blue trigger the coil, the red/yellow, and blue/black are the switch side.
If I hook the red/yellow and blue/black together the headlight comes on with the ignition switch.

So why will the relay not close on its own, but will stay closed once I push it closed?
Sounds like its not getting the current it needs to activate the coil, but I don't know enough about the rest of the wiring to know where the power comes from to activate the coil.
according to the tech manual, the white/blue goes off to a diode block. Could this be the problem?

Thanks for any help.

Peter

 

DEAD RELAY?

try a different one.

 

The headlight relay it tripped by output voltage from the stator. This is to prevent having the headlight load on the battery.

The relay has an internal latch (you should see a diode inside the relay case). This is so once the headlight comes on it stays on unless you turn the motorcycle off. This prevents going dark should the engine stall or the alternator fails. That's why the light stays on when you manually trip the relay.

There is a diode in the white/blue wire to prevent battery voltage being applied back to the stator through the latch circuit on the relay. That diode is in the diode block.

Most likely you have a charging system issue, and you are seeing the symptom in the headlight. Go check your charging voltage, the stator, voltage regulator etc.

 

I just went through the same thing on my bike. The relay is tripped by the wire to the diode block (in my case, in the headlight). That in turn gets its power directly from the alternator/generator. You know that 3-wire connector to the stator? -- yeah, one of those goes to the diode block.

Anyway, in my case it was my own stupid fault - I'd been resistance testing the rotor and stator and had forgotten to hook them up again - so bike would run (on battery only), but no headlight.

I suspect yours might be either a corroded connector, or (and lets cross our fingers not) a bad diode block.

 

There is a quick connect under the seat near the rear fender check that. I had that problem and so did another person I told them and it fixed their problem might fix it for you also. that is the connector that hooks up to the stator.