What's supposed to happen when the low beam quits?

[fredintoon]

My XS11SG has an aftermarket headlight reflector with a 60/55W H4 bulb in it. The low beam failed. Kinda. While subsequently troubleshooting, the filament would light up if I rapped the bulb edge on something. It would also go on and off as I toggled the hi/lo switch but failed again when I put the headlamp back in the bike. Then it give full high beam when switched to high and super-dull high beam with the headlight warning bulb lit when switched to low; just like when it first failed.
WTF, it's in the bin now and the new bulb works fine.
I thought the RLU was supposed to switch the other filament on at full power, not just in a partial manner that don't even show the road at night.
So, is this because of having a different lamp or because the bulb low beam filament was only kinda failed or because the RLU is partially fried or what?

[GARTHXS]

wow!!

I am having exactly the same issue , I think the deal is when the rlu comes on it gives you low intensity high beam, if i read correctly?

[Larrym]

When my low beam failed the RLU switched to high beam (full power) along with showing the Failure lamp.

The bulb was the standard wattage in my case. It also would make/break the connection when I rapped the bulb and turn on and off.

If you dig in the bin and recover the old broken bulb you can reinstall it and check for a voltage drop across the RLU when the switch is in the low beam position. With resistance in the RLU it would likely even get hot after a while.

I don't know if the RLU is rated for the higher amperage of the brighter bulb. If it isn't then full or partial failure of a replacement RLU may happen the next time the brighter bulb fails on either low/high beam.

[fredintoon]

When my low beam failed the RLU switched to high beam (full power) along with showing the Failure lamp.
The bulb was the standard wattage in my case. It also would make/break the connection when I rapped the bulb and turn on and off.
I don't know if the RLU is rated for the higher amperage of the brighter bulb. If it isn't then full or partial failure of a replacement RLU may happen the next time the brighter bulb fails on either low/high beam.

Hi Larry,
the RLU perhaps failing under a higher load is moot.
The H4 in my headlamp has the same 60/55W draw as Clymers sez the bike came with.

[Ivan]

The RLU is probably like anything else on these bikes and showing its age.

[mxmikie]

mine did that so i bypassed it then i had to clean the hi/lo switch and as long as i was messing with it i installed a relay and a 95/145 h4 bulb.............now i can see at night

[Crazcnuk]

The RLU is not supposed to run the high beam at full intensity, that would be rude if not dangerous.

It should run the high beam at lower power, just to get you out of danger (home?).

If the high beam fails, it leaves the low beam at full power beacuse low beam is acceptable to on coming traffic in any situation.

[Larrym]

Daytime..

Right! My lowbeam failed in daylight and so I s'pose my perception of the high being at full power is suspect.

[fredintoon]

Right! My lowbeam failed in daylight and so I s'pose my perception of the high being at full power is suspect.

Hi Larry,
my low beam failed at midnight on an unlit country road.
There was no light at all when it did, or at least, what light there was couldn't be seen above the glare from the headlight warning light. Notwithstanding rudeness I switched to high beam and left it there as a safer option than driving in the dark.
If, as Craz sez, the RLU is SUPPOSED to only supply a reduced voltage to the high beam for safety's sake, my RLU has taken the concept too far. A reduced but visible beam would be OK. A pathetic orange glow that barely serves as a parking light is another matter.

[Larrym]

Mission Mentality

Fred,

I wouldn't miss the next midnight rendezvous with that lonely farmer's daughter on account of your RLU. Leave a bit earlier and drive a little slower in case you have to switch beams underway.

[GARTHXS]

bad ground?

mine does the same intermittently I think it must be a bad ground, because the rlu either functions or it doesnt

[fredintoon]

Re:- mission mentality

Hi Larry,
my midnight ride was not to meet a lonely farmer's daughter.
It was to take my own hot blonde out of the cold dark night and back to our snug motel room.
For that, you stay on high beam regardless.

[Crazcnuk]

"A reduced but visible beam would be OK. A pathetic orange glow that barely serves as a parking light is another matter."

The idea is that you can switch to low beam for oncoming traffic, but use the full beam to get you home....

Of course, in Sask, ANY beam gets lost in the vast nothing that reflects the light!

[CatatonicBug]

This is a pretty educational thread! I actually never knew what the RLU did until reading this... I always knew that if the headlight failed, the warning light would light up on the pilot box, but I didn't realize that it could use the high-beam at a lower power to make up for a failed low-beam. That's pretty cool!

Is it done that way in other bikes too?

[GARTHXS]

so further inspection

upon further inspection, I just checked the ground, and there is no resistance at the regulator or at the switch , so I cleaned the connection and the ground and it seems to work for now , I guess ill wait till it happens again?