Need help ASAP.....6.7.2010 2:30

[Mr. Schweer]

Okay, so I recently bought a super clean, low mileage 81 Special. I've been going through it since it sat for the past few years and today is the first day I've riden it to the office. When I went to lunch, actually, when I got back on to come back to the office after lunch, the headlight warning light came on. No headlight on high or low beam and the highbeam indicator is on. Now I'm certain it's nothing major, but where do I start? I don't want to ride home without the headlight on...even though it'll be light out until 9 tonight.

TIA,

James

[CatatonicBug]

That warning light is simply the RLU's way of telling you that it has automatically switched to using the high beam at a lower wattage because the low beam filament burned out. Just need to replace the bulb.

However, if you don't have ANY light coming from the front, you probably have a short somewhere. Either in the headlight bucket or the left controls (or both).

[psycoreefer]

So High beam indicator and warning light mean that the fuse and headlight relay are working, only three other things in the circuit.
The switch - although the high beam indicator being on would suggest its making contact in the "high" position.
The Bulb - suppose its possible that both beams burned out at the same time?
The RLU - You can remove it but you'll have to jumper two of the wires together, and to get to it you'll have to remove the tank and the seat.

I'd ride it home without the headlight as long as it was "light" outside and troubleshoot in my garage with all my tools.

[Mr. Schweer]

Fortunately its VERY light out, so I can see.....I'm just worried about idiot cage drivers not seeing ME!!
The high beam indicator is on whether the switch is in high beam or low beam and the light is not on at all. I know on my '79 that the tail light will occasionally stop working if the relay gets bumped or moved so I'm hoping it's something simple like that.
What is the RLU?
I'm thinking maybe spray in some lubricant into the switch to help loosen things up. The turn signal switch was a bit 'sticky' when I first got it too.

[Mr. Schweer]

Well.....I got in the bike to leave the office and the light still wasn't on. Went about 40 yards to the first stop light....it came on!!

[CatatonicBug]

The turn signal switch was a bit 'sticky' when I first got it too.

Take that thing apart (all the way) and clean it really good. There are lots of connections in there that sit very close to each other. A small amount of corrosion can really mess things up in there.

[CatatonicBug]

What is the RLU?

It's the "Reserve Lighting Unit". It's a cool little electronic device, mounted next to the Reg/Rect under the tank between the frame rails. If your Low beam goes out, it senses that, and automatically switches to using the high beam filament at a lower wattage to get you home. It can die, but when it's working, I can really save you from a headache.

[Ivan]

I recently had a very similar failure, which manifested almost exactly as you have stated but the headlight would be on very dim on the high element in low position and somewhat dim on the low element with the switch on high beam. Turned out to be a loose connection on the blue/yellow wire at the connector from the left switch under the tank. IIRC the blue/yellow wire is the 12 source for the switch and having partial voltage confused the RLU into doing funny stuff.

The fix was to cut the wires and splice them together with a weather proof butt connector out side the connector.

[fredintoon]

Well.....I got in the bike to leave the office and the light still wasn't on. Went about 40 yards to the first stop light....it came on!!

Hi Mr. Schweer,
when that happened to my bike the bastard kept doing it, sometimes on, sometimes off and the warning light too.
What caused it in my case was an intermittent failure of the low beam filament.
When a filament fails, the RLU switches to the other filament and lights the warning lamp.
But wait! There's more!
If the low beam fails, the RLU switches the high beam on at a reduced voltage.
(On my bike, reduced enough that you couldn't see it at all in daylight and only from in front at night)
It's an alleged "safety feature"
Installed a replacement bulb to fix it.