Low voltage at headlights 10V right 12.5V left?

Trying to wire up a headlight modulator and found this...

When both(left/right) lights are wired none work
Left works when right is not wired and vise versa
One side shows 12.35 when high beams are on, then drops instantly to about 9V after 15 seconds or so
Other side shows high beam constant at 10V+
Had 90W bulb and 45W bulb but I now have x2 55W bulbs
When you wire high beam only and you switch them to low beam, the high beam stays on
Bypassing modulator does not help
Battery reads 14V with engine on.
Previously headlights WERE taking battery bellow 12V with engine on(down from 14v)

Also, my 9 month battery keeps dying on me. Last weekend after a 1.5 hour ride it died to the point that the bike could no longer run anymore. Engine would not stay on anymore.

[Grant66]

A few questions:

Headlight modulator? Is that different from the standard headlight cluster?
Where are you taking the voltage readings from?
Have you checked the earth from the light B/W wire is a good earth (very low resistance to -ve battery terminal)?
Have you tried running the headlight assembly directly from the battery (this isolates the fault to one area)?

Looking at the circuit diagram for a curvey; there are a few other bits powered from the same ignition feed,

It goes from Ignition switch to Fuse 4, Fuse 3, pass light & lighting switch

On Fuse 3 - Fan motor & feed for side stand switch
On Fuse 4 - Horn, Turn signal relay, front/rear brake lights, coolent temp warning & dash indicator lights.

Remove Fuses 3 & 4 and all you have left is the front lighting circuit.

Remove bulbs, disconnect battery, ensure that the live side of the bulb has no path to earth (with ignition and lighting switch to ON, dimmer switch in the appropriate position for the buld contact being tested). if you get anything greater than open circuit reading then switch off ignition then light switch, this will help isolate the problem down to a particular area.

good luck.

Good stuff! Thank you. I'll check tonight. The modulator is the Signal Dynamics modulater. It flashes the lights on and off rapidly making me more visible to cars. I took reading from before/after modulator to make sure modulator was putting out what it was getting. I also checked the source wires on both sides that supply power to lights. Running direct from battery helped initially because I was getting power from the side with 10V output. Now that I'm feeding the modulator from the side with 12V there is no advantage. By side, I'm refering to the 2 sets of power source wires for the lights on both sides of the bike...even though the wiring diagram shows they are actually both coming from the same source, the power is higher on one side. That has to be a big clue huh? How can you take a single wire with a voltage on it and split it out like a "Y" and have more power on one side. Logically the only way I can think of is with resistance on one side. What is the form of resistance?

I feel bad that I have NOT been paying that much attention to grounding so far. Tonight I will completely isolate the wiring harness. I'll do my own ground and power source. If that don't work, then my bike is probably cursed. lol

Originally Posted by gajjii

A few questions:

Headlight modulator? Is that different from the standard headlight cluster?
Where are you taking the voltage readings from?
Have you checked the earth from the light B/W wire is a good earth (very low resistance to -ve battery terminal)?
Have you tried running the headlight assembly directly from the battery (this isolates the fault to one area)?
good luck.

[johnnyrod]

Such a device is a good way to (a) kill your bulbs and (b) **** off everyone on the road. Is this another stupid American idea like the flashing brake lights?

[tigersaw]

If the 'headlamp modulator' is working, then you can't measure a true DC reading anyway, I assume it is based on pulse width modulation in order to get the lamp warm as quick as possible. I doubt you can flash a standard lamp very rapidly anyway.

[Sid Squid]

Originally Posted by johnnyrod

Such a device is a good way to (a) kill your bulbs and (b) **** off everyone on the road. Is this another stupid American idea like the flashing brake lights?

The lamps don't flash perceptibly, the rate is very high, but they do certainly make the light more visible, I had doubts myself but having actually seen this, I agree it does work. I'm not sure that the benefits claimed for the systems are necessarily all absolutely true, but it certainly won't do any harm. Reports from Yankee users known to me suggest bulb life isn't affected.
Flashing brake lights work, end of argument, sadly our construction and use regs don't allow them, same with headlight modulators as our regs prohibit them too.

Actually...no complaints, only positive results. Funny how everyone who does not have a modulator hates it and thinks it won't work. Well from sombody who actually owns one:

People move outta my way on the highway even though I'm not too close to them

Drivers seam to pay more attention

Bulbs have not complained so far(my issue was around to some degree before I got the mod).

Police have harassed me about a LOT of things, but not a word about the mod.

Nobody mistakenly thinks I'm giving them the go ahead

I could not tell you the last time I even had a close call AND my luck generally sucks, so I'm NOT lucky. Got a ticket on my birthday to prove it and it was for passing(After being waved on by driver).

In general it does what it's supposed to do, so from a person who actually has one. I highly recommend it.

Originally Posted by johnnyrod

Such a device is a good way to (a) kill your bulbs and (b) **** off everyone on the road. Is this another stupid American idea like the flashing brake lights?

Thank you. The brake flashers is a very good tool. I think more than modulator for headlights

Originally Posted by Sid Squid

Flashing brake lights work, end of argument, sadly our construction and use regs don't allow them, same with headlight modulators as our regs prohibit them too.

[yorkie_chris]

Originally Posted by F16Falcon

Battery reads 14V with engine on.
Previously headlights WERE taking battery bellow 12V with engine on(down from 14v)

Also, my 9 month battery keeps dying on me. Last weekend after a 1.5 hour ride it died to the point that the bike could no longer run anymore. Engine would not stay on anymore.

So it's not charging right then. Check the alternator output.

It's worst now with new battery. Voltage NEVER goes beyond 12.8V no matter how much you rev. How do I know if it's rectifier/regulator or alternator?

Originally Posted by yorkie_chris

So it's not charging right then. Check the alternator output.