Headlamp issues!

[Presdo]

Whats up! I need some help from the friendly neighborhood gang here!

Heres what i tested:

Lamp works when connected to battery (left and right plug, not the one in the center)
I get readings of power at the headlight harness that connects to the beam
Battery is good
Switch works great

Why doesn't my light turn on! I would like to figure this out. Any ideas?


Thanks
p

 

[HoughMade]

Start the bike and see what happens....and be amazed.

 

[arfstrom]

Different bikes different things, my bike had me convinced it had a bad relay. Then when I got it started, it worked. Okay, My OCD got the better of me, and I also replaced the rectifier, and Voltage regulator, and ... (Chances are I didn't need to. spend as much as I did)

 

[HoughMade]

Start the bike and see what happens....and be amazed.

To be less cryptic, there is a relay that only allows the light to come on after it's started, or at least has fired, regardless of the switch.

 

[Scorpio1963]

That is strange Houghmade cause the light on my bike with come on when I turn the key and not running.

 

[HoughMade]

It appears that yours has been fiddled with in the past.

 

[arfstrom]

You got a jumper, Dont do it, dont do it, Ohhh go ahead and jump! j/k not about the jumper, but the rest

 

[N8Bishop]

mine is the same: light on before it's started. Is there a difference between the '79 and '81? I guess it's not surprising if more than one person would do this kind of mod, but I didn't see any evidence of changes to the harness....

 

[arfstrom]

Alot of times People will take a small wire, close the connection between the "to Light bulb" wire, and the "Always On" wire. usually to ensure the light works, or fears of the relay not working. All that relay is worried about, is that there is enough power to start the bike. instead of sending (forgive the math) 35/65 watts of power to the lights, the starter/Coils, will get first dibs on the remaining battery juice. Then once there is a spark of energy from the stator, it turns on the headlights. Hope that helps.

 

[Scorpio1963]

Houghmade I dont think this is the case,I have taken and inspected all the wiring to the headlamp and all appears intact and normal.
My Dt360 was the same way,always on.I did notice that there are some harnesses inside there that are not plugged into anything.They are with red wires with a black plug.I can take a pic later and post it.

 

[Presdo]

It still doesn't work when I run the bike!

It seems that there is less power up at the headlight than right when it is from the battery. but thats correct, right?

 

[N8Bishop]

What do you mean by

It seems that there is less power up at the headlight than right when it is from the battery.

If you mean the light is dimmer when not connected directly to the Battery.... no that shouldn't be the case unless you are comparing high beam to low beam. There is no headlight current limiting circuit that I am aware of. if it is dimmer (And you are comapring low beam to low beam) then you have a problem in your harness (bad/dirty connections, partially broken wires, etc.)

 

[arfstrom]

If you look at the diagram, there is a diode (on the 81 or so models) that sends one phase directly to the the headlights for extra juice for them. to work in conjunction to the relay im sure. (I think)
Tobie

 

[drewpy]

If you look at the diagram, there is a diode (on the 81 or so models) that sends one phase directly to the the headlights for extra juice for them. to work in conjunction to the relay im sure. (I think)
Tobie

diodes work as a "one way valve" it stops the relay frying with a feedback loop. doesn't actually increase amperage or voltage.

UK bikes don't have to have running lamps and other countries could be the same. So we have no relays for the headlamp.

the relay is there so you can provide as much juice to the starter motor and ignition to actually start the bike. The alternator then operates and energises the relay, thus allows power to the headlamp with the engine running.

the relay is powered by a 4th lead from the alternator as you need 3 for charging

 

[Presdo]

Darn this thing is killing me! I was pulled over for not having it on and received my very own $200 ticket! Huge bummer.

I even spent a good amount of time checking it out and I must be missing something.

So when I looked at it. There is like 12V of power at the harness (One clip connected to the ground and the other clip connected to either of the other two prongs) The switch seems to work because it will switch power on and off of either prong.

Now, maybe the way I tested my head lamp was incorrect. I connected a wire from either of the side prongs to a negative and a positive. It works. (I could be confused, maybe one was ground that was connected).

Thanks again for helping deal with my issues.