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Discussion Starter #1
I put the DP CF shortened tail piece on my S4R tonight. I had to make some wire splices for the turn signals and license plate light--they work fine. The problem is my brake light doesnt work at all--The rear light works and is on, but nothing happens when I apply the brakes. No splices were needed for this, just three clips--red wire,yellow wire and black wire. Any ideas where to start looking ? I assume that the yellow wire carries the brake signal, because I can disconnect it with no changes.

Thanks
 

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First things first.

Check the bulb itself. Might have just burned out.
Check the fuse.

James V
 

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if your fuse is blown better check the wiring to make sure there's no exposed wiring or that the contacts aren't loose in the harness and touching other metal parts....

you could put another fuse in there but if there's a short, you'll just have to put a new fuse in there (after fixing the problem)
 

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Discussion Starter #4
Thanks all for the advice. Could someone with an S4R check the wiring on the tail light for me--there are two prongs close to each other and one off to the side--Stupid me thought I could remember the order. Does the black wire connect to the prong off to the side ?

One thing...I really cant confirm that my brake light was working before I took it off..its something I never really checked. I'm going to check the fuse and bulb tommorrow---is the brake light really on a different circuit (fuse) than the tail light (the taill light works fine)?
 

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As mentioned above, I would go and get a heavy filament replacement bulb first...I had the exact same prob after that mod, bought a new bulb - Problem Solved ;D
 

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Discussion Starter #6
Thanks---I'm thinking it must be the bulb--I got the wiring diagram out--turns out the brake light switches are on the same circuit as the horn which works fine. I'm going to get a new bulb today. Whenever I have to do electrical stuff I always think I screwed something up :)
 

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I would get an LED bulb personally. I went through 3 filament bulbs in under 2 weeks after I chopped my tail. Bought a high quality 48-LED cluster bulb and no problems for over 10 months...
 

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Discussion Starter #8
The problem isnt the bulb :(-- But changing the bulb showed me one thing...both filiments are always lit--I put on a volt meter on and found out that each of the two leads, red and yellow are always hot when the bike is on--wiring diagram shows the red lead coming from the brake switches.... must be a problem in the switch ? Anybody else agree ? I think it must be unrelated to the tail mod ?
 

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Maybe the wire is pinched shorting out the running light wire to the brake wire during the mod process.
 

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Check the front brake switch. Mine popped out of the lever housing and I had the same symptom. The switch is on the underside of the mount. If the switch isn't pressed the brake light will always be on.
 

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Discussion Starter #11
Looks like its my rear brake switch, the little black (plastic ?) stem is all munged up and doesnt move in and out freely, it probably cant retract fully. I'll have to wait until next week to get it fixed. Thanks everyone !
 

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munged???? as in dirty, gunky, rusty, ????
 

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Discussion Starter #13
munged???? as in dirty, gunky, rusty, ????
munged as in broken--it fell off completly now--the switch is still stuck on though. I'm getting it looked at tommorrow.
 
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