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Discussion Starter · #1 ·
Just discovered the following on my 2012:
Inboard bulbs on trunk only function as running lights - There is no additional lighting on braking as there should be. The outer trunk lights never illuminate (I believe they should light on braking only). The running light in between the turn signals functions as running lights, but the right bulb brightens on braking. My add on Kuryakyn LED lighting on the lower rear functions correctly as both running lights, then brightens on braking as it should. No changes have been made to lighting since I got the bike in 2013 other than the add on Kuryakyn lights installed in 2013. All fuses seem fine and the bulbs are good. At a loss and not sure where to go from here. Thoughts?
 

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Discussion Starter · #3 ·
Sure. I actually also own a service manual…..just don’t know how to read electrical diagrams. I do have a friend who is an electrician, so any help is appreciated.
 

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As you know, the four bulbs in the trunk are all dual filament (tail and brake lights) but two have only one power wire to them. Some bikes have four tail and two brake and some bikes have four brake and two tail (as a side note, Electrical Connection makes a kit to make all four work as both). And you also know that the light between the turn signals also had dual filament but factory wired as a tail light, no brake wire (again, you can convert to both functions). You said this is all factory wiring.

Since it works correctly, where does the Kury light gets its power from? Because that works, my first thought is that you have a bad OEM bulb and it is acting as a false ground. Especially since the center light is getting brighter - it has no wire to light that filament! It's possible that the factory ground connection is unreliable but that doesn't match all the symptoms. Test or change out some of those bulbs. You can even use the turn signal bulbs for testing.

Happy Thanksgiving.
 

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Had similar problem a couple of days ago while doing a inspection, Brake lights did not work from hand or peddle activation. Blubs looked fine, but replaced outer bulb (Outer bulbs in the on rear lights are the ones that show braking) on left side with new one to test and that fixed the problem. Bulb looked fine was bad. Try replacing the outer bulbs with known good ones and see what happens. As a side note, during this inspection I found that the foot brake switch had gone bad also, so part now on order..
 

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Discussion Starter · #6 ·
Thanks, guys. I did switch the outboard (non lit) bulbs with the inboard working bulbs. Same result as the inboard bulbs lit as running lights, but do not activate on braking. The Kuryakyn lights came with a jumper that plugged directly into the connection under the back center panel that feeds the turn signals and fender light. They are the only thing functioning correctly.
I too suspect some type of ground problem for the trunk lights, but have not been able to find it. Since the Kury lights work on both hand lever and foot pedal, I believe the brake switches are working correctly. Gotta love electrical issues.😉
 

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I would get everything working right before adding that new jumper. BTW, I did not add the trunk wire jumpers. Mine were like yours, two inboard as tail and all four as brake and I thought that "popped" better. I did add the F6B harness so the lower center light does both tail and brake light.

Curious now. The Kury light plugs in behind the center tail/turn signal combo light. There is no brake light feed there. Some of the aftermarket lights pick up the brake inside the trunk lid where the Honda harness feeds the accessory spoiler. Does it have this as well? Not a big deal as regardless of where it gets its brake feed from, it shouldn't cause your problem. Just isolates potential sources of the problem.

Still suspicious of why the center tail light gets brighter without a brake light feed.
 

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Discussion Starter · #10 ·
Ditto on the center light AND why only one bulb. I did switch out both bulbs and bases on the trunk lights to verify that all 4 bulbs and bases appear to work. Of course I've not been able to test the brake function. It must be a short somewhere, but it looks like tracing the trunk light wiring is a real PITA. BTW, I reported yesterday that the right bulb on the "fender" light brightened on brake application.....today it is running light only. My buddy reminded me that a couple of days ago, it was the LEFT bulb that brightened on brake.
 

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The diagrams can be difficult to follow. If you look carefully you can see the wire colors are called out on each diagram.
 

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IF the dual filament bulb is working for running but NOT for brakes. The issue isn't a missing ground. The ground is common for both filaments. I might start under the seat. The connector that has everything in it is on the right side of the rear plastic inner fender. You have to dig for it. Below is a pic of a break out jumper harness that Steve (M61A1Mech) made. It is THE connector that has brake, L Turn, R Turn, Run, Trunk release etc in it. I'd find it, pop it apart and probe for the all of the signals. The colors of the wires are the same as in the diagram posted above. This pic was taken on the left side of the bike facing the trunk.
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This pic was taken standing on the right side of the bike looking forward. The connector of interest is hanging over the frame. Its mate is towards the rear behind the relay box.

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Discussion Starter · #15 ·
Problem solved and it was two separate issues. As background, I bought this 2012 in 2013 with 300 miles on it. Apparently the previous owner had run additional wires to the taillight between the turn signals to make it also a brake light. Those wires ran up into the trunk lid and I discovered they'd been caught in the hinge hardware. Both we frayed and separated in such a way that they were able to make intermittent contact which is why it appeared to sometimes flash on brake application. At the under seat connector that k2mpw showed above, I discovered he had apparently also put in a brake modulator and one of the wires to it had come out from the crimp on connecter he used. Now all 3 wires are soldered and shrink wrapped, and the lights all work. When I get the Electrical Connection jumper I ordered, all 4 trunk lights will then work as running and brake lights.

Everyone I ride with assumed I only had the lower lights for braking, so there's no telling how long the trunk lights had not worked correctly. It was only when the fender mounted light no longer worked that someone brought it to my attention. Appreciate all the help as talking through it with you all helped me isolate the issue.
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Glad it's all fixed and that you came back and shared with us. Don't take this wrong but you should think about T-CLOCS. I do a walk around and check all the lights every day before I leave the garage. Important to know what everything is supposed to do and that it does it.
 

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Discussion Starter · #18 ·
Glad it's all fixed and that you came back and shared with us. Don't take this wrong but you should think about T-CLOCS. I do a walk around and check all the lights every day before I leave the garage. Important to know what everything is supposed to do and that it does it.
Glad it's all fixed and that you came back and shared with us. Don't take this wrong but you should think about T-CLOCS. I do a walk around and check all the lights every day before I leave the garage. Important to know what everything is supposed to do and that it does it.
Good point and I actually do. Problem is when I activate the brakes, I can only stretch to see the lowers and they were activating. All running lights were operational as well as turn signals. I rarely ride with other Wing riders so no one noticed anything amiss until this last weekend’s ride. Anyway, all good and the forum helped me get it fixed. Cheers!
 
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