It's a plug under the rear seat

 

There is a large round barrel plug under the passenger seat, just in front of the trunk rack. Should have a blank cap on it.

Not sure which wire you need, as BMW hasn't released an official wiring diagram for this bike yet.

I'd look for a Brown wire first, as Brown is Ground on Bemeers, the use a meter or test light to probe the other wires while somebody flashes the brakes on and off . . .

 

Skeene design (Skene Design Motorcycle Visibility Lights) has pictures of how to connect his controller to the GTL connector under the seat. I'm assuming the connector is the same for the GT. I've done this mod on my bike using a light strip from super bright led. Based on my "reverse engineering" the brown wire is ground, the red wire is the tail light, and the grey/black/yellow wire is the brake light.

 

My .02 and experience...

Right Turn - Blue w Black tracer + White dots
Left Turn - Blue w Red tracer + White dots
Tail - Gray w Black tracer
Brake - Gray w Black tracer + Yellow dots
License - Gray w Red tracer + Yellow dots
Common (Ground) - Brown

 

The red in the plug is positive with the 2 minute timer. Powers the light in the top case.

 

That makes sense for the Skeene IQ-160 box I used--the red wire is used in his GTL top case wiring diagram to provide the flickering "tail light" function. When I turn my key off the lights keep flickering for a minute or so.

I wonder if the light stays on inside the top case when the key is on. If so, my backpack wouldn't be left in the dark. Sounds like a refrigerator light conundrum.

 

it turns off when the lid is closed. must be a micro switch in the handle/ latching mechanism. Yes, I put my phone to record video and put it inside to see!

 

...I put my phone to record video and put it inside to see!

Just another clever use of the smartphone

 

Hey Top_Speed, I think you mean the Tail wire is Red . . .

Might want to edit that to avoid future confusion.

 

By Tail; do you really mean the [Red] Top Case Courtesy lamp wire? If so, I did not include that in my wiring codes BUT I did update it to include the 'tracer dots' (some wires have them)..

 

You can also access the brake light wire inside the access panel on the right side. One of our customers has provided these instructions:

To access the tail light assembly wiring harness remove the side case on the throttle side.
Remove the small bike colored side panel.
The wiring harness is held in a metal clip behind the side cover just below the passenger grab handle. The wires are contained in loose piece of rubber tubing. The tubing must be removed to access the wiring.

Light......................... Wire Color Code

Right Turn Signal.... Blue w/ Black Tracer; repeating White dots

Left Turn Signal .......Blue w/ Red Tracer; repeating White dots

Tail Light ..................Gray w/ Black Tracer

Brake Light.............. Gray w/ Black Tracer; repeating Yellow dots

License Plate ...........Gray w/ Red Tracer; repeating Yellow dots

Ground .................... Brown

 

Light......................... Wire Color Code

Right Turn Signal.... Blue w/ Black Tracer; repeating White dots

Left Turn Signal .......Blue w/ Red Tracer; repeating White dots

Tail Light ..................Gray w/ Black Tracer

Brake Light.............. Gray w/ Black Tracer; repeating Yellow dots

License Plate ...........Gray w/ Red Tracer; repeating Yellow dots

Ground .................... Brown

For 2018 GTL UK model, the wires are as follows:-

Blue/Black = ignition on lights,
Yellow/Brown = Right indicator,
Blue/Brown = Left indicator,
Orange/Brown = Brake light,
Green/Brown = Common Earth.

 

I dont have the PDM yet but safe to say if the trigger wire is hot for 2 mins past the key being turned off, the PDM is still hot for 2 mins. I think the tail light is instant off, (gray
w/ black tracer as listed above should do it.

 

Thanks, guys. A little project added to the list!

 

this was a very helpful old thread as I am wiring a brake light in my Givi top case but I do have a question. I found the barrel plug with the wires under the seat and also determined which wire in the plug lights the brake light. But my question is: do I try to find wire connections that will plug into the appropriate pins or do I just splice into the wire before it gets to the barrel plug? Where would a find such a little connector?

thanks in advance for your help.
Wayne
2015 GT

 

I used a positap to connect to mine. Leaves the stock wire intact if you remove it to sell the bike.

Sent from my Pixel 2 XL using Tapatalk

 

Thanks. I checked into the posi-tap suggestion and looks like a great product. Ordered a pack today.

 

Either a posi-tap or use a female pin that fits over the male pin inside the connector like I did.

 

Either a posi-tap or use a female pin that fits over the male pin inside the connector like I did.

Yes, that's what I was thinking. Where does one find such a pin?

 

@Jonnybow, I'd put my money on a Deutsch connector pin, 18-22 gauge...

Duane