Dim headlight question

[XSive_speed]

Hi all,

I'm chasing down a problem with my headlight being dim. It has been this way since I bought the bike, so I didn't really think much of it until I started tracing it with a meter. The first thing I noticed when trying to read voltage across the bulb is what I considered an odd wiring configuration.

On the low beam, voltage was between the Green (High) and Yellow (Low) leads. This seems very suspect to me for two reasons. First, if for some reason they were using both filiments in series, I would still expect to read half voltage between either green or yellow and black. Second, My understanding is that generally the headlight should be wired to use one filiment or the other, but not both. Am I wrong here?

The second problem is that with the bike off (started first to engage the relay), I am only seeing about 8.5V across the headlight. This says I am doping the other 4V somewhere in the connectors, the reley, or the aux headlight unit. Ok, I know where the aux headlight unit is, but I'm not sure about the relay. Can anyone tell me? Then I will proceed with tracing the voltage drops and cleaning connections.

Thanks,

XSive_speed

[GLoweVA]

The head light relay is under the tank up front near the bars above the ignition coils.
It's a 4 wire. 2 for the headlight Red/yellow (hot) & Blue/Black (to Reserve lighting unit) and 2 to turn relay on White (from alternator) and Black (ground)

If both the green and yellow are getting voltage then it sounds like the reserve lighting device isn't working properly.

[XSive_speed]

The head light relay is under the tank up front near the bars above the ignition coils.
It's a 4 wire. 2 for the headlight Red/yellow (hot) & Blue/Black (to Reserve lighting unit) and 2 to turn relay on White (from alternator) and Black (ground)

If both the green and yellow are getting voltage then it sounds like the reserve lighting device isn't working properly.

Ok - that's a possibility I had not really considered yet. Do you know what voltages I should measure on the reserve lighting device pins in the "normal" low beam and high beam conditions? I took a quick look at 3Phase's schematic, but its not immediately obvious to me exactly what should be on the wires, but I can probably put together a good guess with some experimentations.

[ManagerMike]

The relay is under the tank just aft of the sterring head.
Low beam is the green wire, high is the yellow, they share ground. Any voltage readings you pick up between the high and low circuits are likely due to the rlu and the way it monitors and controls the headlamp.
My bet is the relay dropping your missing voltage.

[crazy steve]

A couple of things that need clarifying...

Are you saying you don't have voltage to ground on either headlight wire? If not, you need to fix that before going any further. And you are checking with the headlight lamp installed, right? If it's missing from the circuit the RLU will attempt to power both feeds. If the ground is missing, you would get the same issue.

And yes, only one filament should be powered at a time.