Weird headlight voodoo on 1100

[johnstewart]

I email the y-triples list about this, but thought I'd give y'all a try, too.

I've owned a 79 XS750SF for 10 years, and a couple of weeks ago just bought a 79 XS1100SF. I've got the thing pretty well fixed up, except for some headlight weirdness over which I've been banging my head. Can anyone help me out?

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Well, I did a bunch of work on my newly acquired XS1100SF on Saturday,
hoping to be able to also get some riding in:

- Installed tkat fork brace
- Replaced front brake lever/master cylinder
- Replaced front brake pads
- Bled front brake lines
- Swapped in better mirrors (still rust but somewhat better looking)
- Took off horrible looking luggage rack, remounted rear signals properly
- Tried to fix tach; slightly better with some lube, still jumpy
- Changed oil (used Mobil-1 5W-50 red cap)
- Fixed signal cancel switch (was gunked up, would not cancel)

After all of this, I was ready to take the girlfriend to the movies on the
fixed up bike, after working from noon until 9, when I turned it on and...
the damn headlight won't come on any more. Had to take the Honda. Sigh.
Also, I had to take her to the new Jenifer Aniston movie; freaking awful
movie (The Good Girl). She did feed me many times as I worked on the bike,
so I guess it's a wash.

The 1100 headlight worked pretty okay (the hi/low beams were inverted; the
PO had taken off a fairing and didn't wire it back up properly, and it had a
habit of not always coming on until the engine was running), but it worked
fairly reliably before I worked on the bike this Saturday.

I spent many hours today trying to sort out what the problem could be.
Thanks to 2 parts bikes (both 750's), I was able to try replacing a lot of
parts.

I'm really at a loss here guys, and frutrated as hell. I wanted to spend
most of my weekend crusing around, not playing voodoo with the electrical.
If anyone can give me a pointer, please, please do. I don't want to lose my
CBMMA membership by having to take this thing to the shop for something that
*seems* so simple. It's only a damn headlight, right?

The only thing I can think of that would have affected the electrical is I
took the rear lights off of the luggage rack and mounted them in the
original mount holes. I had to find the ground wires, but it was pretty
obvious, and I mounted them just as they were on my 750. *They* seem to work
perfectly. I've tried unplugging them again, but that doesn't seem to have
any effect on the malfunctioning headlight.

Things I've tried:

- As mentioned above, unplugged the ground and main wires for the rear
signals, which I had installed this weekend.
- Swapped in a known good headlight
- Swapped headlight relay (not known good, from old parts bike)
- Swapped reserve lighting unit (ditto)
- Disassembled and desoldered hi/lo light switch, cleaned, reassembled.
Tested and it appears to operate as designed according to wiring diagram.

Things I've noticed:
- Rear light does go on with main switch, and brake light does work (gets
bright when either brake is used)
- Speedometer/tachometer does *not* light up with main switch

Also, and this may be a big clue to someone who has more of an idea how in
the hell this thing is suposed to work, is as follows. The wires to the
headlight seem to be black for ground, yellow for low beams, and green for
high beams.

- When testing connectivity (with no headlight in socket), the yellow wire
is always at ground (there is connectivity between the yellow wire and the
engine block) whether the high or low beam is selected. It appears from
testing on my 750 that yellow should be at ground when the high beams are
selected, and the green should be at ground when the low beams are selected.
On the (misbehaving) 1100, the green behaves this way, but the yellow is, as
I said, always at ground.

So I'm thinking maybe the yellow wire is somehow grounded improperly. But
I've been searching for anything apparent and have not found it. I don't see
any frayed wires touching any metal, etc... but tracing the damn yellow
wires is pretty difficult since I'm not quite sure where physically the wire
splits and where it is intended to go.

I have the wiring diagram I found online:

http://members.fortunecity.com/imlucky/fullwire.htm
(warning; apparently lots of popups)

But that's all I'm going on.

Please tell me there is something easy and obvious I am missing...!

thanks

johnS

[Mike Hart]

Hi John

Yellow should never be at ground (or green), that's voltage source, black is ground. (does black show short to yellow?) That yellow is also voltage source for high-beam indicator bulb, and goes to the RLU too. Unplug the yellow from the RLU and see if you still see yellow short to ground.

Oh, you didn't mention - did you check the fuse? Fuse box is a weak point, notorious.

If fuse is good, are you really sure the RLU is ok?
see http://www.xs11.com/forum/showthread.php?threadid=874

[johnstewart]

Ahhh! I was wondering what in the sam hell the reserve lighting unit did.

I did swap it out, but with a unit that had been sitting in a bike that hasn't run in 10 years or so. I will either try swapping it out with the one from my 750 (which works fine) or will try just wiring past it (which actually sounds like it may be the best idea).

I'll test it all tonight.

thanks!!

[johnstewart]

Sigh... no joy.

I took out the RLU and wired the blue/black and blue/yellow wires together. Same problem. Yellow to headlight is always at ground regardless of hi/low position, and light doesn't work when plugged in.

I did find that when I unplugged the 4-way harness going to the tach with Sb (sky blue), G (green), Y (yellow), and L (blue), that then the yellow wire at headlight appearred to work as expected in that it was only at ground when the Hi beam was selected.

However, the light still didn't work.

I think I may have screwed the thing up by spraying silicone lube into the tach trying to get the fluctuating tach problem fixed. I tried disconnecting both harnesses going to the tach (the abovementioned one and also the one with the W (white) Br (brown) and B (black) wires. I think perhaps that the silicone lube created a short from the Y to the ground wire in the tach.

However, even with both harnesses disconnected going to the tach, it's the same problem. Also, the tach *does* still work.

Fuse is good (get connectivity on all fuses by testing against wires on either side of fuse assembly); the fuse box is actually in pretty good shape (much much better than my 750 looked when I got it).

I have little doubt at this point that I screwed things up by spraying lube into the tach, but if that is the case, I can't figure out why the light won't work with the 2 tach harnesses disconnected. Obviously the high beam indicator wouldn't work, but why not the headlight itself?

Argh... any more ideas?

I'm precariously close to hauling this thing to the shop and pay out the nose for them to sort it out.

Thank you

[Mike Hart]

Yellow shouldn't be at ground when hi-beam is selected. How could the light work if both ends of it are at ground?

Are you sure that when you took apart and re-did the hi-lo switch that you didn't wire it up that way? with yellow grounding?

Check your switch again, maybe yellow is grounding there, and it shouldn't. On hi beam, yellow connects to blue/yellow, green connects to light green. On lo beam, blue/yellow connects to green, yellow connects to light green.

[johnstewart]

Originally posted by Mike Hart
Yellow shouldn't be at ground when hi-beam is selected. How could the light work if both ends of it are at ground?

Well, this is definitely how it works on my 750, and that bike's headlights work just fine.

I'm obviously no expert, but my understanding is that of the 3 wires going to the headlight, yellow is for low beams and green is for high beams, with both of them using the black wire as ground.

Thus, it makes sense that the opposite wire would be at ground when the other is live.

Are you sure that when you took apart and re-did the hi-lo switch that you didn't wire it up that way? with yellow grounding?

Check your switch again, maybe yellow is grounding there, and it shouldn't. On hi beam, yellow connects to blue/yellow, green connects to light green. On lo beam, blue/yellow connects to green, yellow connects to light green.

Pretty darn sure I got the switch right. I tested that in fact:

Hi -> yellow to blue/yellow and green to blue/green

Low -> blue/yellow to green and yellow to blue/green

I'm 99% certain the switch is working fine. It tested as the wiring diagram specifies, which is (almost) identical to my 750's behaviour. (I say almost because the 750 has an additional yellow/black wire going to a contact on the switch, while the 1100 has the yellow wire jumpered to 2 contacts).

Something else is amiss. I'm sure I screwed something up with my tach "repair", but if that is the case what else did I break in the process?

Would disconnecting the tach normally cause the headlights to stop working? I wouldn't think so, so if my hypothesis is true, I messed up something else when I shorted things out. Perhaps the headlight relay?

[Mike Hart]

Ok, switch sounds good.

From what I can tell, you have it backwards tho - yellow is high, green is low. Yes, it makes sense that the one not selected would be at ground (thru the RLU).

So, if you select high, and yellow is then at ground, that isn't right, according to the schematic and diagram I am looking at.

The tach and headlight relay both get a signal from the alternator. Have you determined that the headlight relay is working as it should?

I'm pretty sure on the SF that the headlight should be off with engine not running. When the alternator is spinning, that activates the headlight relay, which also feeds the meter lights. (I'm an XJ guy, headlight circuit is different - light is on with key on, goes off when cranking, comes back on when running.)

We'll get it. Don't send it to a shop!!!!! They'll just charge you a lot to screw it up worse.

[johnstewart]

Originally posted by Mike Hart
Ok, switch sounds good.

From what I can tell, you have it backwards tho - yellow is high, green is low. Yes, it makes sense that the one not selected would be at ground (thru the RLU).

So, if you select high, and yellow is then at ground, that isn't right, according to the schematic and diagram I am looking at.

Okay, could be. Although I was pretty sure it matched the behaviour on my 750. Regardless, switching the yellow and green wires should be pretty trivial once I get the major problems sorted out. =)

The tach and headlight relay both get a signal from the alternator. Have you determined that the headlight relay is working as it should?

Yes and no. I did swap in a different relay from one of my parts bikes, but that was with the tach still connected. I'll try replacing it and trying again with the tach (the source of my problems, I still think) disconnected.

We'll get it. Don't send it to a shop!!!!! They'll just charge you a lot to screw it up worse.

Heheh... yeah, and charge me 75 bucks an hour for flailing around helplessly just as I am. I do trust them for many things (we've got a great independent shop here in Madison, WI), but damn, I want to fix this myself.

I also had a suggestion on the triples list to check the voltage from the stator wire to the headlight relay while the bike is running. I think my plan for the next round of attempted repair:

- Remove tach (this should *not* stop anything else from working, right?)
- Check stator voltage to relay.
- Replace headlight relay with known good unit (I know the one on my 750 works).

Thanks for your help!

[johnstewart]

Well, I'm not sure what I did to fix it, but it's working...!

I think that perhaps the lube finally dried up at some point.

Last night, I removed the tach, still no good, then I went to check the voltage on the wire from the stator to the headlight relay.

Then I realized the whole thing might work better if I actually plugged in the headlight relay!

d'oh!

At some point in my troubleshooting I'd disconnected it and forgot to re-attach. When I plugged everything back in, including the tach, it *all* works.

Thanks for the help!