79 xs1100 special electrical question

[lowprofile2000]

Hi guys,

I am new here as I just purchased this 79 xs1100 with 7400 miles from craigslist. Its not currently running, so I am doing the basics, oil changes, carb cleaning etc, the bike is clean but has been sitting for at least 17 years based on the latest registration.

while the cleaning is in progress I have an electrical question, can someone take a look at this pic? it appears to be aftermarket wiring of some sort(I could be wrong), any ideas? the first of many questions I assume.

thanks for your time.

https://1drv.ms/i/s!Ao2JA7ZOTynImfIT-BNNtQW7dgbeVQ

https://1drv.ms/i/s!Ao2JA7ZOTynImfs1kXX3Uwbjj1Q2Rg

[lowprofile2000]

[TopCatGr58]

Hey there,

Scott/3Phase is our current active electrical guru, so he may see and post also.
You're right, the stock 79 SF doesn't have anything behind the TCI towards the rear of the bike. I think I can see the blue wires that go to the rear running light, think I see a brown and a faded/light green....they may be going to the turn signals but can't tell for sure? That box is TAPED DOWN, not sure if it's a mod for the turn signals or what???

In the tech tips, there are wiring diagrams in color that you can use to try to match up the colors and what they go to on the bike, ie. rear tail light, turn signals, etc.!

You'll probably need to take that thing off and trace the wires to what they go to and then report back here if you can't figure out what's what!

T.C.

[3Phase]

Lowprofile2000,

The wire colors aren't stock and whatever it is has been grafted on.

It could be a lighting modulator for fancy lighting effects when signaling and braking, or it could be a booster/isolator for extra lighting.

[lowprofile2000]

thanks guys, I guess I will learn more once I get a battery! I will let you know what I figure out.

[3Phase]

Thinking about it after coffee this morning, it could be an anti-theft alarm.

[lowprofile2000]

Turns out it's a taillight coupler, whatever that is!

[TopCatGr58]

Hey Low,

Were your rear turn signal lenses RED instead of yellow?? I tried searching for that thing, NO GO, thinking if you have Red Rear signal lenses that it was to make the turn signals into extra brake lights???

T.C.

[lowprofile2000]

Hey Low,

Were your rear turn signal lenses RED instead of yellow?? I tried searching for that thing, NO GO, thinking if you have Red Rear signal lenses that it was to make the turn signals into extra brake lights???

T.C.

No, they are yellow, appear to be factory, I could not find that thing online either.

[sethhope]

After some searching I think topcat's right. It is for using the turn signals as extra brake lights. Looks like whoever put it on just never changed the lenses. May not have even finished hooking it up. My recommendation, trace the wires and REMOVE safely (unless you plan on changing the taillight lenses)