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BMW Supplemental Brake Light Wiring Questions


The Rocketman

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The Rocketman

I got a GREAT deal on a BMW Supplemental Brake Light. I have questions regarding bench testing it, and installation.

I cut off the proprietary BMW/AMP connector to make everything easier, and am NOT going to buy the BMW OEM wiring harness for the installation.

 

 

(1) There is a red, gray and brown wire. How would I connect these on a bench to a battery to verify functionality before installing it into my '09RT?

 

(2) When installing it (not using the available harness), and using my FuzeBlock FZ1, could I assume red goes to a switched hot to the FZ1, gray goes to the hot side of the brake light bulb, and brown goes to a ground (also in the FZ1) ??

 

Thanks for the help and advice.

 

Larry

 

light_zpsnlogpaml.jpg

 

wires_zpseicgwltq.jpg

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Morning Larry

 

On the BMW brown is ground so I would hook the brown to battery (-) then try the red then the gray to battery (+).

 

What bike are you going to use that on??????

 

If on your 2009 1200RT that bike uses a funny brake tail light with ONLY one wire feeding both the tail light & brake light.

 

The computer pulses partial (6-8v) voltage for tail light & then goes to full 12-14v for brake light.

 

That light you have may be a problem getting to work on that 09 1200RT without upsetting the light monitoring system.

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The Rocketman

It came from an '09RT and is going on my '09RT. I already have HyperLites on the bike tapped into that funny wire, and just want more brake lights.

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Afternoon Larry

 

OK, I thought you had the early (non can bus era light)

 

I have (had anyhow) a wiring diagram of the light that you have but can't seem to find it at the moment (it was in paper form not electronic)

 

I'm trying to remember how that was wired (it came with a plug in harness)

 

I'm thinking that the brown goes to ground, the red goes to battery (+) fused & the gray goes to your tail/brake light wire.

 

Without the diagram it is only a guess though.

 

You might call your local dealer as I bet they have an install/wire diagram that you could look at.

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With the official harness, this system connects at the connector for the rear power port and then with a Y-terminal to the (one) tail light bulb wire.

 

This means that two of the wires provide constant power (positive and ground) and the third wire is the activation wire, which is the tail/brake wire. Clearly the assumption is a USA-spec bike with headlight/taillight always on.

 

Since it's the same wire for both tail and brake, your light will run dim all the time and when brake is activated will flash very quickly for about a second and then remain steady bright until brake is released.

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The Rocketman

Got it. Was wondering why there might be 2 (+) wires. The brake light activation wire is the one I didn't figure on. So you think if I touch both simultaneously to a battery (+) post and ground the brown, I should be able to bench test it? Based on what I'm reading above, if I just juice up the red wire, I should see a dim light; then when I add the gray wire, it should brighten up and (maybe) flash?

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Got it. Was wondering why there might be 2 (+) wires. The brake light activation wire is the one I didn't figure on. So you think if I touch both simultaneously to a battery (+) post and ground the brown, I should be able to bench test it? Based on what I'm reading above, if I just juice up the red wire, I should see a dim light; then when I add the gray wire, it should brighten up and (maybe) flash?

 

Afternoon Larry

 

I'm not sure-- it depends on IF the red wire is for internal circuit power or is to operate the tail light.

 

The red could be for internal power circuitry & the tail light is then operated from the reduced power (pulsed) tail/brake light wire just like the OEM tail brake light bulb is.

 

I guess try it-- if the light glows at about 1/2 power with the red to (B+) & the brown to ground then it gets brighter with gray to (B+) then you have your answer.

 

On the other hand it no 1/2 power with brown to ground & red to (B+) then that red wire is probably just for internal circuitry control & it will take pulsed input on the gray wire to get tail light the full 12v on the gray to get brake light.

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The Rocketman

No joy with any combination of wiring bench testing with a known good battery last night.

 

(a) Light might be shot. E-mailed seller to confirm they previously saw it work.

 

(b) May need BMW harness. E-mailed seller to see if they still have it, although I really don't think I need it.

 

© May just try temporarily wiring it to the bike to see if that makes it happy.

 

(d) Imprinted on the red lens is CODE3 and a bunch of numbers. These lights might be made by the Authority police light guys. Might ask them for some advice.

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The Rocketman

Everything is under control. The Ebay place I bought this from said it was working. It is dead as a door nail. They refunded my money. Turns out the BMW Supplemental Brake light actually shares its guts with a very similar model(LC25STT) made by Code3. I contacted their tech support line just for advice yesterday, and even though I didn't buy it from them, they cut me a solid, and are sending me a brand new, updated version of the LED light part, for free as a courtesy. What a stand up guy and a stand up company. Sometimes things just work out :)

Can't wait to get the new guts and get this installed.

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Great news.In case someone else has a similar issue - were they able to confirm if test wiring straight to 12v will work?

 

Please follow up with a photo of the replacement light when it arrives. I'm on my second BMW led and if this one tanks, I'd like to see the updated version. Looking at Code3's website, it's not clear what light they are sending you.

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The Rocketman

They don't have this one on their site. Its called the "low cost stop turn tail light". I'll let you know if their replacement module fits, and if its a direct 12v install. I have the installation manual on a .PDF I can send you later on, but I'll know before the install when I bench test it to a battery on the work bench. Trying to avoid buying the BMW harness. Their replacement just has 3 wires (ground, switched hot & trigger got) with no BMW/AMP connector, so I'm pretty confident it will work fine.

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The Rocketman

I received the replacement 16-LED module from Code3 today (LC STT T07944). It is an exact match for the non-functional one that came with the used BMW Supplemental Brake Light I just purchased. Only difference is when I bench tested the replacement, I nearly went blind. This thing is stupid bright as a running light, and even brighter as a brake light. Holy cow! Don't know why I stared right at it, but I'm still seeing spots. It even came with a brand-shiny-new red Code3 lens cover, which it shall wear proudly once I get around to installing it. For those who have these lights that don't light anymore, I think we've found a fantastic source for replacement parts. Don't know exactly, but can't imagine the LED replacement module costs anything near what a new light would cost from BMW.

I'll post photos tomorrow of the old & new modules just for future reference, and will update this thread after the install.

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Great! :thumbsup: Thanks for sharing and for taking the time to post photos. Please keep us updated on how you end up wiring the replacement unit.

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Mounting is a separate question, but ...

 

I like this supplemental light but it's a little heavy and the fact BMW thinks the number plate can be held on by sheet metal screws screwed into plastic seems dubious when adding more weight.

 

I enlarged the holes and now have bolts/nuts doing this job. TORX to keep with the prevailing theme.

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The Rocketman

Getting there...

Had to spend some time this weekend installing Zumo 660 cradles & wiring harnesses on 3 bikes, to replace the old StreetPilot 2720 setups I had. Took a few hours for each bike.

 

Last night I soldered 3' extentions to the Supplemental Brake Light wires, and picked up a few of these Twin Piggyback connectors, to plug into the brake light bulb, so I don't have to tap into the wire, as I already did that with my HyperLights.

 

Will be using a switched hot and ground on the FuzeBlock FZ1. Just need a little time to get the install done and route the wires nicely. Will post when its a wrap.

 

piggy%20back%20connector_zpsxpj8py7v.jpg

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Morning Larry

 

On the BMW brown is ground so I would hook the brown to battery (-) then try the red then the gray to battery (+).

 

What bike are you going to use that on??????

 

If on your 2009 1200RT that bike uses a funny brake tail light with ONLY one wire feeding both the tail light & brake light.

 

The computer pulses partial (6-8v) voltage for tail light & then goes to full 12-14v for brake light.

 

That light you have may be a problem getting to work on that 09 1200RT without upsetting the light monitoring system.

 

I used that same unit on my '09 RT and had no problems wiring it directly to the installed brake light following the enclosed instructions. Worked properly right away. Only problems: the flicker is VERY quick and 1/2 the LEDs burned out after 2 years. Still, the remainder are working fine and still very bright.

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The Rocketman

The Code3 LC STT T07944 replacement 16-LED module lists for $ 69.57. If 1/2 your burned out bulbs bothers you a lot, I guess you could buy the replacement light fixture, or if you catch customer service on a good day and whine a little, maybe they'll ship you a freebie :)

 

Always worth a phone call...

(314) 426-2700 (Central Time)

Main Office hours 8:00 a.m. - 5:00 p.m.

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The Rocketman

OK so I got the LED light wired up and installed yesterday.

I ran the red wire from the light to a switched 12v (+) on my FuzeBlock FZ1.

I ran the black wire from the light to the (-) side of the FZ1.

I ran the gray wire from the light to a piggy-back spade connector on the (+) gray striped side of one of the brake light bulb sockets.

It lights.

Just hard to tell if it lights correctly. Its so simple, there's no way to do it wrong.

Turning key on, LEDs light up as a running light.

Applying the brakes, LED light flickers for milliseconds, then goes solid. Like its supposed to.

Just seems to me there's very little difference in the intensity of the light from running light to solid brake light. If there is a difference, its barely noticeable.

If I unplug the gray trigger wire, and apply the brakes, obviously no flicker and no brake light; just running light.

If I unplug the gray wire, apply the brakes, then while applying the brake, plug in the gray wire, the intensity from off to on is definitely more visible. As in the difference in intensity is greater. Seems the brightness is correct with brakes applied, but it seems that in running light mode, its almost too bright.

12 volts is 12 volts.

Any ideas, or is this how this light is supposed to work?

I can't imagine the bike and LED light is supposed to get less voltage as a running light, then increased voltage when the gray brake trigger light is applied. But I've been wrong before.

2 other people saw it, and although they noticed a slight difference in intensity, we all thought the difference should be more noticeable.

I will keep it either way as its super bright, but would like to hear from those that have it themselves, or if anyone has any suggestions.

Also wondering since only 1 hot wire runs to each of the dual filament brake/tail light bulbs, if that is a clue???

Thanks.

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Any ideas, or is this how this light is supposed to work?

I can't imagine the bike and LED light is supposed to get less voltage as a running light, then increased voltage when the gray brake trigger light is applied.

 

Morning Rocketman

 

I'm not sure how THAT light is supposed to work but my homemade rear LED tail/brake lights do work on less voltage for running light & 12-14 volts for brake light.

 

Your bike's tail/brake light is a single wire with (pulsed) 6-8 volts for rear running light & a full 12-14 volts for brake light.

 

If your added light assembly gets RUNNING light power from the red wire then your light intensity is what it is & brake light intensity is only as bright as the power from the gray wire.

 

It might be possible for you to add a resistor in the red wire to lower the running light intensity but still keep the current brake light intensity.

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The Rocketman

Thanks for the suggestion. I sent a note to Code3 tech support and will wait to see what they have to add.

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The Rocketman

So I've spoken to 2 BMW techs and both said they've tried wiring the supplemental brake light the way I did, and it never worked properly. They said the CANBus is s strange system, and recommended I spring for the correct harness to get my light to work. Before I do that, I'd like to try the resistor route. Watched a few videos about it, and a little confused. They basically say to wire in 2 equal resistors in series, and then at the point they join, the voltage drop should be 1/2. Trying to figure out what size resistors to use, and do I put them both on the red switched hot leg? If I do that and put them in end-to-end, where do I tie in the hot wire, since I'm already installing them into the hot wire itself? Do I do anything with the ground wire too? Specific instructions would help a lot.

Thanks.

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So I've spoken to 2 BMW techs and both said they've tried wiring the supplemental brake light the way I did, and it never worked properly. They said the CANBus is s strange system, and recommended I spring for the correct harness to get my light to work. Before I do that, I'd like to try the resistor route. Watched a few videos about it, and a little confused. They basically say to wire in 2 equal resistors in series, and then at the point they join, the voltage drop should be 1/2. Trying to figure out what size resistors to use, and do I put them both on the red switched hot leg? If I do that and put them in end-to-end, where do I tie in the hot wire, since I'm already installing them into the hot wire itself? Do I do anything with the ground wire too? Specific instructions would help a lot.

 

Morning Rocketman

 

Fist things first-- The CanBus might be a strange system but it nothing to do with powering your rear lighting. CanBus allows the ZFE controller to talk to the dash controller & brake controller & tell the dash controller to illuminate the light-out warning but the CanBus is just the communication system between on-bike systems.

 

On how to resist the rear supplement light that you have?- You will need to know the resistance or your supplemental light, or know what the internal regulator is, or know the working current of that rear light. (or just take a guess at it & see if it works)

 

Personally I would call the supplier of that rear light & talk with their tec help people. If anyone would know how to reduce (resist) the running light without effecting the brake light function they should.

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The Rocketman

As crazy as I know this is going to sound, I found the problem just now. Can't explain it, but the LED light is now functioning perfectly. Lower brightness as a running light, and noticeably higher brightness as a brake light. All I did was unplug the red constant (+) wire from the Fuzeblock, to see what would happen. It works great. Apparently just the gray brake trigger wire is enough to make it work. Would love to know why, but sometimes it just doesn't matter.

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The Rocketman

Code3 Tech Support just said:

"Larry,

 

I am pleased to know that you are satisfied. I did some checking into your vehicle and the led module based on your last email.

Your vehicle apparently uses CANBus. The original part is a CANBus Stop-Turn-Tail Module. The part that you recently received

Is a non-CANBus Stop-Turn-Tail Module. Unfortunately, Code 3 stopped providing the CANBus version of the module five years ago.

Both versions are similar.

 

Do you think that the red wire was always energized? The red wire is supposed to received a switched 12 volt DC signal."

 

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Larry - Thanks for updating this thread. Sounds like the Code 3 may be cost effective alternative to to the factory supplemental led light. So just the gray wire to the brake, leaving the red wire disconnected was the solution?

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The Rocketman

Yep. The red wire is absolutely not necessary since the newest Code 3 light module is a non-CANBus Stop-Turn-Tail Module. Just tap the gray Code3 light wire into the gray striped wire to either brake/tail light bulb socket, ground the brown wire anywhere you want, and cap off the red one. Easy, now that its all been worked out. Works perfectly on my '09 RT.

 

Just remember the Code3 LC25STT or T07944 light only comes with the light module and a red lens. You still need the plastic housing and metal mount that came with the BMW light, unless you can think of another way to mount it. The stock light also came with a rubber O-ring, which appears to have no purpose, but I re-used it anyway.

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The Rocketman

The FuzeBlock wasn't the issue. Having the constant red wire connected to any source of 12v+ was the issue. I even connected the red wire to the 12v rear accessory plug like the BMW harness would do, and had the same problem. The cause was that the LED module was a non CANBus module rather than a CANBus module. Now that the red wire is disconnected it works properly using just the gray wire.

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