Headlight not working

[3Phase]

It will work.

I used the ubiquitous and inexpensive 1N4001 from Radio Shack when we had one but they're long gone.

Amazon has some ceramic bead diodes that would be better for the heat from continuous operation but it's a pack of 25.


Original 25pcs/lot BYV26C Ceramic Fast Recovery diode 1A 600V SOD57 ic c1
by QSKAII


https://www.amazon.com/Original-25pcs-BYV26C-Ceramic-Recovery/dp/B07XXKS4BX/

[thebottle]

Thanks Scott.

I ordered a 5 pack of 1N4001, the ceramic ones wouldn't ship to me until Jun 25th and I don't want to wait that long.

[3Phase]

While you're waiting for the 4001s, use a jumper and bypass the relay.
L/B to R/Y (Blue with Black stripe to Red with Yellow stripe)

I left mine bypassed and ditched the relay, then quit worrying about the diode and the relay. When the relay or diode fails then the headlight doesn't turn on and Head warning light doesn't glow.

It's sometimes hard to see the warning light in full daylight and it doesn't come on to tell you if the headlight failed.

The RLU won't automatically switch headlight filaments because the headlight is not on.

[ardvark1]

Talking about headlight not working.
I'm working on me SF thats been off the road for 12 years.
When I turn on the ignition the clock lights and rear tail light come on as they always did BUT the headlight don't.
The question is :- Is the headlight suppose to come on with the ignition or is there something in the system that only lets the headlight come on when the engine is running?

[thebottle]

Talking about headlight not working.
I'm working on me SF thats been off the road for 12 years.
When I turn on the ignition the clock lights and rear tail light come on as they always did BUT the headlight don't.
The question is :- Is the headlight suppose to come on with the ignition or is there something in the system that only lets the headlight come on when the engine is running?

It will only come on after the bike is running, but you can jump the relay like 3Phase said and then it will come on with the ignition. The relay is the little square box under the tank just above the ignition coils. The problem I had was the diode, I decided to replace it (works great now, ), but if this one doesn't last long then I'll likely jump the relay and not deal with it any longer.

[skids]

I use the light off/on switch (78E models) to switch the low current side of a “light relay.” It is a nice option.

[cajun31]

Diodes can still be bought

from Partzilla. https://www.partzilla.com/product/ya...90834583f3f3bf. Don't have to be soldered. They come with the connectors on each end and there is no way to install it wrong.

[thebottle]

That's like $18 with shipping, , and a 3-5 day wait for them.

I got 5 for $3.50 and free next day shipping. I just used the original ends and soldered the new one into them. Pretty easy.

[cajun31]

I am just posting

so others that read this thread will know. By the way... the diode you are replacing probably lasted for almost 40 years. It will be nice to have the other two in case someone might need one from you. Also... soldering these wires, although everyone does it, is not good for the wire. I prefer just buying one ready to install. Just did about 6 months ago and after replacing it and it not doing anything for my headlight not working went on to replace the headlight relay which was the source of the problem all along. Go figure.

[Loch]

head light

The diode is a one-way director for the AC current flow out of the alternator to energize the Headlight relay so the light comes on only after the engine starts. Make sure the relay works too.

[skids]

OR, run DC to a switch on the bars and down to the relay where the diode circuit comes in. If you are worried about remembering to switch it on, just leave it on. I did away with the “reserve lighting unit” and relay and put in a switchable lighting relay. If you do leave the lights on and start the bike, there will be less current to the headlight than you might think because the starter is like a direct short in terms of current. The ability to switch off the headlights is a real advantage at times. You can get a switch like the 78s have.

[thebottle]

so others that read this thread will know. By the way... the diode you are replacing probably lasted for almost 40 years.

Nah, it's been wired wrong because of this when I bought it 10 years ago, and who knows when it actually became a problem.

Also... soldering these wires, although everyone does it, is not good for the wire.

How come? The joints are soldered onto the connectors on the one's you linked no? I don't see a difference, interested to know why. I left the connectors on the actual factory wires.

I prefer just buying one ready to install. Just did about 6 months ago and after replacing it and it not doing anything for my headlight not working went on to replace the headlight relay which was the source of the problem all along. Go figure.

I ruled that out first with another relay from a parts bike. There was some thread I searched and found on here that walked me through everything.