rewiring the existing tail light to become a brake light?

[Slaphappygamer]

I haven't purchased the bike yet, probably going to buy it this weekend after i test ride a couple of other bikes. On the 700 series, has anyone tried to rewire the tail light to act as a brake light? Could we possibly tap into the line that cuts the motor off when actuating the brake and use that pulse to communicate with the tail light? I've searched, but can't find much info.

Or perhaps, I could use a different light fixture assuming the wires are already in place. Hmmmm

 

[ki11a]

There are many tail lights that are available for purchase on Amazon that have a brake stop light feature...when it senses that you have pressed on the brake, the tail light will turn on. They are mostly externally battery powered and are rechargeable, which I think is better than hooking it up to your controller and possibly messing stuff up.

 

[BigNerd]

I have one of those speed sensing lights... surprisingly enough it's works pretty well (annoyed my biking group because I kept asking them... "Is it brighter now?" "How about now?" "Follow down this hill and tell me when the light gets brighter.").

 

[Slaphappygamer]

I just pulled out my controller to see what I have. It’s an lsw1155-29-6m. I can’t find the wiring diagram for it. Anyone have it? I do see other diagrams and they have 3 wires going to the brake light. I’m guessing that my controller doesn’t have a “brake relay?” to wire my existing light to, but I don’t know for sure. I did get an external light with an accelerometer to use for braking, for the time being.

Also, I have this red and gray wire not connected to anything. Anyone know what that does?

 

[Slaphappygamer]

Wow, ok. So I've been doing some research. I found that the existing tail light (Buchel Edge) has an accelerometer built in. I found the product page here. How can this feature be used? I looked real close and I do see the 2 outer leds on the tail light exist on my light. In the video of the product page, you can see that those are the same leds that illuminate when braking. If that feature is standard, in the light itself, then how could it be "enabled"? I also started think that there must be a similar tail light that can replace this one.

 

[Slaphappygamer]

Turns out, this is there is a newer version of the stock light. Here is an article explaining the "new version for 2021". This new version has the "sensor technology that detects the deceleration of the speed during braking". If I can find the new 2021 version of this light, itll be a straight swap.

 

[Slaphappygamer]

So, I bit the bullet and ordered this kit.

Amazon.com

It comes with a wiring harness that has the same SM-2 connectors that connect to the controller. I’ll have to make a male to male SM-2 adapter for the power as I’ll be using the existing brake light power to feed this kit. I found out that the existing tail light runs at 52v.

The kit should be here in about a month, so we will see how this all comes together. I’ll update when I get this installed. I’m super stoked!

 

[Slaphappygamer]

I just installed this kit. I used the power from the existing rear light as my power source, for this. I had to make a male to male sm adapter so this kit will accept power. Other than that, this was plug and play (well, mostly). I did have to reverse the wiring between this kit (brake input) and the controller (brake output). That was in the product description though, so it wasn’t a hard fix. When I turn the lights on, from the display, this kit gets activated. The controller, for this light kit, has a clicky light button. The button will stay depressed when you press it, then it releases upon the next press. I can just leave it depressed and just use my displays light button to turn the lights on and off. Anyhow, the turn signals work as expected. The brake light illuminates when activating the brakes

 

[Blasst]

I just installed this kit. I used the power from the existing rear light as my power source, for this. I had to make a male to male sm adapter so this kit will accept power. Other than that, this was plug and play (well, mostly). I did have to reverse the wiring between this kit (brake input) and the controller (brake output). That was in the product description though, so it wasn’t a hard fix. When I turn the lights on, from the display, this kit gets activated. The controller, for this light kit, has a clicky light button. The button will stay depressed when you press it, then it releases upon the next press. I can just leave it depressed and just use my displays light button to turn the lights on and off. Anyhow, the turn signals work as expected. The brake light illuminates when activating the brakes

Nice job! You should make a short video of the lights in action. I wish a system like this came with bikes when purchased, I would like it as I do a lot of street riding with autos.