MINI Cooper SE Visible Brake Light Modification

The electric MINI Cooper SE illuminates its brake lights when the driver presses the brake pedal and autonomously when the driver initiates regenerative braking by lifting off the accelerator pedal. The MINI Cooper SE does not provide any indication of this autonomous brake-light illumination to the driver so the driver has no way of knowing at what point the MINI Cooper SE illuminates its brake lights. This article describes a modification designed to provide such an indication.

The goal of this design was to implement the simplest modification that could provide a visual indication to the driver whenever the brake lights are illuminated. Anticipating that such an indicator might be considered intrusive by some drivers (perhaps by all drivers, with time), the indicator needed be easy to disable.

The most minimal indicator I found readily available was a 1.8 mm LED. Red was chosen because that is the color of brake lights. To simplify the wiring, the chosen LED included a wired-in resistor to make it compatible with 12-Volt power. I purchased 49 more LEDs than I needed for $10.99 on Amazon.com: EDGELEC 50pcs 12 Volt 1.8mm Red LED.

1.8 mm red LED photo


The most convenient access to the brake-light signal is within the high-mounted, center brake light housing. A forward-facing LED mounted in this housing can be viewed by the driver in the interior rear-view mirror.

The center brake-light housing inside the hatch can be removed without any tools (see disclaimer at the bottom of this page). Pry the right side away from the hatch window to get a finger behind it. Then increase pressure slowly until the fastener clip pops out of its hole. Then move your finger(s) left and pull the housing to release the second clip. Continue moving left, releasing the remaining 3 clips.

Center brake-light housing photo


Pull the electrical power-supply connector out of the center brake-light LED strip. Then you can remove the center brake-light housing from the hatch. Using a T-20 star-driver, remove the two screws securing center brake-light LED strip to the housing.

Center brake-light electrical connector photo


Almost the entire front of the housing is obscured from the driver's view by the car's headliner, so to be visible, the LED must be centered at the bottom of the front side of the housing. Drill a hole behind where the center brake-light LED strip was mounted and in front of the center retainer clip. To accommodate the 1.8 mm LED selected for this application, I drilled a 5/64" hole in the housing. A hole this size is so small that it will be unnoticeable except when the indicator LED is illuminated.

Viewing aperture for brake-light indicator LED photo


The bottom edge of the center brake-light LED strip covers the location of the hole drilled for the indicator LED, so a section of the bottom edge must be removed. I used a hack-saw to make 2 cuts in the bottom edge and then broke off the section between the cuts. Be careful not to break off more than the intended section of the bottom edge.

Modified center brake-light LED strip photo


Insert the front of the indicator LED into the hole drilled in the housing and glue it against the support for the fastener clip. I used a clear, flexible gel-adhesive called "Goop," because I found it in my box of adhesives and I never trust super glue. I taped the indicator LED in place above where I applied the Goop and removed the tape after the Goop had set.

If you are handier than me, you can re-mount the center brake-light LED strip in the housing so you can determine how far the indicator LED can be angled away from the support to improve its visibility from the front of the car. After you determine the maximum angle that will not interfere with the center brake-light LED strip, you can fashion a thin wedge to let you glue the indicator LED at this angle. Make sure you can route the indicator LED wires behind the center brake-light LED strip towards the power-supply connector.

Gluing the LED indicator in place photo


Immediately after gluing the LED indicator in place, ensure the LED is visible through the hole in the housing.

Ensure the LED is visible through the hole photo


Obtain a 2-wire connector or 2 single-wire connectors to make it possible to disconnect the LED indicator should the housing need to be removed in the future. Attach the connector(s) to the LED indicator wires and the corresponding connector(s) to a new pair of wires (I stole mine from a sacrificial LED). Splice that new pair of wires into the wires that supply power to the center brake-light LED strip. To do this I removed some of the tape holding the two power-supply wires together, cut the wires about 2.5 inches from the connector, stripped the new pair of wires about an inch from the end, slid 1.5 inches of heat-shrink tubing over the wires attached to the power-supply connector and the new pair of wires, wrapped the inch of stripped wire around the power-supply and connector wires, soldered the connections, moved the heat-shrink tubing over the soldered joints and shrank the heat-shrink tubing.

Splicing into the center brake-light power supply wires photo


Reattach the center brake-light LED strip to the housing while making sure to route the indicator LED wires behind the strip. Bundle the indicator LED wires and attach them to the center brake-light power supply wires with a twist-wrap.

Bundle the indicator LED wires and secure them photo


Test the operation of the center brake-light and the indicator LED. Then reattach the center brake-light housing to the top of the hatch. Test again.

Testing the brake-light indicator LED photo


From the driver's seat, press the brake pedal to see the indicator LED in the rear-view mirror. Now you can decide for yourself if it was a good idea to use such a tiny LED. However, before tearing the housing off the hatch to install a larger LED, read on to see how to make the light from the tiny LED more visible.

Viewing the brake-light indicator LED in the rear-view mirror photo


To increase the visibility of the indicator LED (for example, on a bright, sunny day), you can cut a small piece from a Post-it Note™, fold it slightly, and affix it to the center brake-light housing so that the indicator LED shines down on the folded part of the paper.

Increasing indicator LED visibility photo


If you decide that the indicator LED is more annoying than informative, simply cover the hole with a small piece of electrical tape.


Commentary

It was disappointing to discover how little regenerative braking is required to illuminate the brake lights. Regardless of whether I chose High-Energy Recovery or Low-Energy Recovery regenerative braking, I found the brake lights flash on and off frequently as I drive. I am using the indicator LED to train myself to know instinctively when I'm displaying brake lights to the car behind me.

Some tail-gating drivers see my MINI Cooper SE's display of brake lights as an aggressive driver-instigated signal to back off. Other drivers probably assume I'm carelessly driving with my left foot on the brake pedal. My goal is to prevent the brake lights from flashing on and off in short, random-seeming bursts.

The most surprising and disturbing behavior I noted was that the brake lights go dark after the regenerative braking brings the MINI Cooper SE to a complete stop. So if you want to be sure the driver of the car coming up behind you realizes you are stopped, remember to use the brake pedal to illuminate the brake lights.

I wish the MINI engineers could have developed an artificial intelligence that would illuminate the brake lights more appropriately. Evidently, MINI's lawyers deemed even the level of deceleration typically provided by engine-braking in a gas-powered MINI to be dangerous without illuminating the brake lights of this electric vehicle. Where were those lawyers when it was decided a stopped MINI Cooper SE would not always illuminate its brake lights?


Disclaimer

Any person performing the modifications described above is entirely responsible for any injury to themselves or their MINI Cooper SE and entirely responsible for any accident that results from staring in the rear-view mirror when they should be watching the road in front of their MINI Cooper SE.