Headlight Stopped Working after removing mysterious Switch

[KMFW]

New 650 hacker, so bear with me. I just got a '79 XS650 - SF I believe (2F0-160678 - more on this SN in a second). When I got the bike, the guy a bought it from had installed a switch that - he said - disabled th headlight so the engine would start with the starter... as if the headlight was draining power. Anyway, the switch was ugly, so I ripped it off. It had wires (two leads from the switch) wrapped around a couple of connectors in the headlight. Like the grand-duffis I am, I did not pay attention to where it was connected as I figured it was a hack job and superfluous.

Now the headlight does not work. No power. No Joy.

I have a Clymer manual, and it indicates (for my model number and SN above), that this model is supposed to have a headlight on/off switch (later models, it appears, did away with this). Well, mine does not have said switch (but my serial number match engine and frame, so I am fairly sure of the model, and diagram). I suspect a previous owner replaced the throttle-side controls with a unit without the switch, and added the switch I so brilliantly ripped out.

So, HELP! I have no idea how to get the Headlight working again. Hot-Wire is fine - I do not need to turn it off. But the wiring I see in the headlight does not match Clymer's wiring diagram.


So, HELP! I have no idea how to get the Headlight working again. Hot-Wire is fine - I do not need to turn it off. But the wiring I see in the headlight does not match Clymer's wiring diagram.

Many Thanks

 

[bluebikerblan]

I've had a few of both the 79 SF and the 78 SE. The 78 SE's usually had the headlight on switch....the 79 SF's usually did not. However, the cut out of power to the headlight when the starter was actuated was accomplished via the safety relay (inside the right side cover) in both cases and not a manually operated switch.

I suspect that you're going to need to spend some time with the wiring diagrams of both to ascertain which version wiring harness your bike was supplied with originally. The model with the headlight on/off switch on the right handlebar had a blue/black wiring from the safety relay to the on/off switch and was usually listed as a 78 SE. The 79 SF had no switch nor blue/black wire and was the first of the "headlight always on" models. Frankly, I always liked the simplicity of turning the headlight on or off and being able to run my bikes without the headlight being on....which is daylight legal in Utah btw. And have bought several such 78 right hand controls with the switch and converted later models with the change.

My model information disagrees with your conclusion (from Clymers) re your bike being originally equipped with a headlight on/off switch and shows VIN #'s 2F0-150101 to 2F0-250101 to be XS 650 SF (ie no headlight on/off switch). The 78 SE's with the switch usually went from 100101 to 150101

This may well not be the only variance to the stock wiring of whatever model it is. I would suggest that you spend sometime figuring out from the wiring diagrams supplied on this site which one you have and how much or what else might have been changed and what is and is not connected at the safety relay. Lots of folks changed lots of things in the past 33 years on any bike still around.

Be of stout heart, all will be sorted out. Guru's abound on the subject. Best, Blue

Here's the 78 WD for the SE with the switch for example...

View attachment 526

 

[KMFW]

Thanks for the reply, Blue. I will dig into this more - as you say, in 30 years, anything could have been done to this bike.

BTW, could you enlighten me as to the function of the Safety Relay, the Light Checker, and the Reserve Lighting Unit? What are these things doing?

Thanks,
KMFW

 

[TwoJugs]

The reserve lighting box keeps the headlight off until it senses engine rotation, start. Then it turns on the headlight. designed to save battery life and allow more voltage to the ignition circut for a moment. It resets back to headlight off every time the keys switch is cycled to the off position.

 

[txpowdercoater]

What!!? [insert threadjack here] where is this reserve lighting box and how does it work?
I want one. I have an 81 harness, dont remember seeing an animal like that.
I have my "kick only" xs wired through the neutral relay to kill the headlight in neutral for easy starting, this sucks majorly and would rather have an item that automatically keeps the headlight off until motor is running, thats cool.

 

[bluebikerblan]

The reserve lighting box keeps the headlight off until it senses engine rotation, start. Then it turns on the headlight. designed to save battery life and allow more voltage to the ignition circut for a moment. It resets back to headlight off every time the keys switch is cycled to the off position.

I believe you've mixed up the functions of the "Safety Relay" and the "Reserve Lighting Unit"....The RLU senses the high beam of the headlight being out and switches the low beam on should that occur and lights an indicator light as well.

 

[bloodthirstysystem]

http://www.excess650.co.uk/tips & tricks.htm

"Anyway locate this offending device, usually under the seat behind the battery and unplug it, (early ones are black, later ones are grey ) then sling it over the nearest hedge, Now looking at the plug that comes from the loom connect the Blue/Black wire to the Blue/Yellow wire and normal headlamp operation & sanity is resumed."

 

[bloodthirstysystem]

txpowder.. if you still want one you can have mine. haha

 

[bluebikerblan]

Reserve Lighting Units, RLU...Turn Signal Cancelling Units, TSCU....Light Checking Units, LCU....Sidestand Down Interlocks. All candidates for chucking and overall simplification of wiring IMHO. Also all covered in numerous previous posts both here, and 650rider.com achives complete with photos of units, description of location and mods needed to ensure continued operability.

"Sure makes a pretty colored bunch of spaghetti on the garage floor" as Guru #9 might say. Blue

 

[KMFW]

Yeah, lookin' like minimalism is the way to go. Thanks for all the tips.

-KMFW

 

[bluebikerblan]

BTW, could you enlighten me as to the function of the Safety Relay, the Light Checker, and the Reserve Lighting Unit? What are these things doing?

Thanks,
KMFW

Safety Relay....cuts power to headlight when starter is actuated and prevents actuation of starter when motor is running.

Reserve Lighting Unit....switches power to low beam if high beam not working and lights indicator light.

Light Checker....detects failure of tail/brake lights and actuates indicator light.

Self Cancelling Turn Signal Unit....cancels turn signals at the switch.

Sidestand down interlock...prevents engine from starting/running with sidestand down (late year Specials).
----------------------------------------------------------------
Dump the 'Clymers' (way too many errors) and use the factory service manual such as is available online here:

http://www.knucklebusterinc.com/tech/XS650.pdf

Blue

 

[rayth]

Folks - I am building an 80SG
I have MikeS RH switch whicha allows me turn my lights on/off
I have learned how to bypass the "reserve lighting" gadget -but it appears as if other functions are involved - ie; the neutral switch-perhaps other
Would anyone have a schematic of the Reserve Lighting switch please showing the ins/outs of the wiring
Any advice much appreciated