Blinking Brake Light

Check out the whole video for step-by-step visuals if you want to follow along!

(1) Brake Light

(28) Red LED Diodes (7) 180 ohm 1/8w Resistors (1) Prototyping board (1) Arduino Nano (1) spools of wire (1) 8 pin waterproof connector optional (2) Male/female spade connectors

This step will vary from car to car, but generally you want to remove the brake light assembly from the vehicle.

I used a wood burning tool to cut the plastic around the housing. You can definitely use a dremel with a cutoff wheel here, but I find that it flings hot plastic balls everywhere which isn't nice.

Whatever you use to cut it open is fine, just need to be sure to cut along the perimeter that can give you the most access to the internal components (i.e. closer to the lens part)

The two halves should look something like this.

At this point, there may be a diffuser between the back half of the light and the lens. You do not really need this, but it also doesn't hurt to keep it.

Whether you use a dremel of hot knife to cut the housing, you end up with melted plastic around the edges.

We used a small pair of pliers and they break off easily.

Also used a utility knife to get the edges smoother, but this isn't necessary.

We had a large sheet of prototyping board and cut it down to match the inside dimension of the housing.

We measured the protoboard and had to sand down some high spots on the light housing to get a snug fit

You can use 80grit sand paper or a dremel tool will make quick work. Worst case scenario you can carve away at the hight spots with a utility knife.

The LED arrangement was 7 parallel circuits of 4 series LEDs.

Although maybe not the best method, we made make-shift traces for each series circuit by overflowing solder from one point to the next.

We wired everything to have independent ground legs (to the arduino) and a common positive 12v (from the car side brake light switch).

The power (Vin) for the arduino is also tapped from the car brake light switch. Not sure this is the best method, but it allowed us to avoid running additional wiring through the car. This approach keeps everything "plug and play"

We used an Arduino nano with a simple blinking program.

Basically D2 - D8 are digital outputs to the LED Circuits and D9 is the input from the car side brake switch

The digital inputs cannot exceed 5v (as far as I understand), so to protect the arduino I used a USB charging adapter.

Taking off the plastic housing, grounding spring and the USB port we soldered wires in the respective places.

To keep things modular, we used a 8pin waterproof connector.

We crimped the pins onto each wire making sure to include the waterproof boot.

Before inserting the pins into the connector, we routed the wires through the opening of the 3D printed enclosure we modeled.

We did the same thing for the LED board by routing the wires through the plastic housing and connecting the wires into the corresponding pins

Now that everything is seated into place, we matched the two halves of the light together and hot glued it around.

Once everything is sealed up we can use an external power supply and check it out in action!