headlight diode question

[clintinga]

Hey guys. I was tidying up the wiring today on my xs and I noticed that the headlight diode was missing. I have searched thru the forum and I have found some info on it but everyone else who had a problem with the diode, their headlight wasn't working. Mine does work so, of course I am going to replace the diode but I was wondering if anyone can explain why my headlight works and the diode is bad?

Regards,

Clint

 

[drewpy]

diodes only let electricity flow in one direction. if one fails, it could also let it flow in the other direction but the lamp will still work as lamps will work either way.

 

[clintinga]

Thanks for the reply drewpy. I understand but the diode was missing completely and the wires the diode connects to were not making a connection. That is what I am wondering about.

Regards,

Clint

 

[drewpy]

do you have running lights or only when they are switched on?

 

[clintinga]

Hmmm, when I turn the key on, the headlight and tail light come on. As far as running lights, I removed the stock turn signals and replaced with single filament signals, so no running lights. I am not sure if that is what you were asking.


Regards,

Clint

 

[drewpy]

might be connected (excuse the pun) But I also think your lights should come on when the engine starts via a relay and the diode may be off that.


someone else can chime in as its regional specific and the UK spec is a little simpler

 

[Onetype]

That diode is for the incoming charge from the alt to the headlight relay which switches on the headlight once the bike is started. Since your headlight is coming on when you turn the key on it would seem that the P.O bypassed the whole thing. I wouldn't worry too much about it, I bypassed mine and put the headlight on a toggle switch when I was troubleshooting my charging problem and haven't looked back.

 

[clintinga]

Thanks drewpy and Onetype. I am just going to leave it be then. Onetype, one last question, did you connect the wire together where the diode was, thus removing the diode or should I keep them apart?

Regards,

Clint

 

[Onetype]

It's been a while since I did this but I removed the headlight relay, there was no reason to keep the wire containing the diode so I terminated it pretty close to that point. Without knowing what has been done to it exactly I would just leave it be, doesn't seem to be causing you any issues. If they are already apart you might as well just tape up the wire since it isn't doing anything. I wouldn't connect them without a diode if the relay is still connected just to be safe.

 

[clintinga]

Thanks Onetype. I will give it a try and see what happens.

Regards,

Clint

 

[drewpy]

That diode is for the incoming charge from the alt to the headlight relay which switches on the headlight once the bike is started. Since your headlight is coming on when you turn the key on it would seem that the P.O bypassed the whole thing. I wouldn't worry too much about it, I bypassed mine and put the headlight on a toggle switch when I was troubleshooting my charging problem and haven't looked back.

so what the diode is doing is a form of voltage rectifying (rectifiers have 4 diodes) and this stops the AC pulses from affecting the DC relay and feeding back to the alternator.