DIY Brake Light
Disclaimer: I started this project thinking that getting both bulbs (brake and running) to light independently would be trivial. While it was trivial, it was more time consuming than I planned due to the design of the light I used (grounds for both bulbs in series). If you want to use the whole light as just a brake light, or just a running light, you can be done a lot quicker.
- soldering iron and solder
- wire (I used 16awg)
- Crimp on quick-disconnects (if desired)
- Marker light (be sure that the marker you get has 2 bulbs; I bought a clearance light and it only ended up having one)
- Gluegun or other adhesive
- needle nose pliers
- Remove lens
- Remove bulb assembly from plastic base. There are two plastic rivet-things holding it in; I pulled mine out forcefully. If you took more time, you could probably get it to go back in without using a gluegun.
- There are two exposed contacts (A and C), one with a black wire running off it stock (A), and the other free. Use a dremel cutting wheel or other implement to cut the free contact as far to one side as you can.
- Remove the bulb and pull the shorter contact out carefully with needle nose pliers.
- Flip the bulb assembly upside down. Use the dremel and cut the metal ground/base plate (B) in half down the center. I made two cuts to ensure clearance between them so there would be no continuity. (not shown)
- Bend the longer contact down and solder it to its closest the ground/base plate foot (Opposite B, in my case).
- Use the dremel wheel to cut out the side of the bulb assembly on the side where the shorter contact goes (D).
- Strip a wire and solder it to the outside of the shorter contact. Insert the contact back into the bulb assembly.
- Use shrink tubing or glue gun and fill the area where the contacts were cut (C) to ensure no connectivity between the leads.
- Strip a wire and solder it to the foot of the longer contact's base plate (Opposite B).
- Use dremel or file to open up the wire hole so all 3 wires can fit through the back plate.
- Feed the wires through the wire hole and reattach the assembly to the base plate (I used glue gun on one side).
- Strip the ends of your wires and attach crimp on quick disconnects if desired.
I'm using a brake switch that allows electricity to flow (closed connection) when the lever is pulled. This is true for many tomos switches. In this case, I have a positive (hot) line from my stator to A. Opposite B's ground is grounded to the frame, and D's wire is ran to the brake switch, and then grounded to the headlight bucket's ground. When the brake lever is pulled, electicity flows to the brake light.
Alternatively, if you have a switch that allows electricity to flow (closed connection) when the brake lever is not pulled, you can do the following (Puch). Run your gray wire from the stator to the running light (Opposite B, in my case) and ground the black wire to the frame (A). The green wire from the stator gets split into 2 lines (usually this is done with the stock wiring block, with two lines connected opposite green in the block). One wire runs up to the brake switch, and the other brake switch wire is grounded (can use headlight ground). The other wire runs to the brake light. The prinicpal is that because the connection at the brake switch is always closed, and the lightbulb is effectively a resistor, electricity will flow along the path of least resistance and go from the stator to the switch, and be grounded. When you pull the brake lever, the path is cut off, and electricity follows the path of the brake light.