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Lights – How to Improve Trunk Lighting, Model 3

There are a number of ways to improve the trunk lighting.  You could replace the two existing LED modules with brighter ones. Our Footlight LED Enhancement page goes into great detail – either modify the modules or buy new ones from a third party.

We elected to go with a custom design that dramatically brightens the trunk area with an array of LEDs that cast less shadows and improves the color rendition of the trunk lighting. No cuts, holes or adhesives are needed to install this project, and it can later be removed without any effects to your car.

before and after trunk lighting

Before and after photos taken with the identical manual camera settings.

We also created a plastic hardware-free LED mounting lens that doesn’t use adhesives. While you could mount the LEDs with the strip adhesive on the back of the LEDs, they tend to fall off in high heat typically encountered in vehicles.

It’s hard to buy only the parts necessary for this project. We’ve tried to source the smallest quantities, but there will be some excess.  We made small number of Parts kits on eBay for $30 with free USA shipping. It includes all the parts including the TT 3D printed mounting bracket. We also have available a limited number of Fully assembled and tested units for $45 on eBay.

If you get your own parts, you may be able to replace some parts with those you have on hand. All the parts cost us $164 plus about $20 in shipping. This results in some excess!  Assembly and installation after the parts are acquired should take less than 30 minutes.

Parts
  • 1 TT 3D printed LED mounting bracket (See below; using 3DHubs, ~$15 or to print yourself HD glass filament reel $52 for 360 grams)
  • 4″ LED Strip, with 12 super-bright LEDs, CRI > 90, 3000K, 12VDC, high-density ($58 for 5 meter reel)
  • 3 feet 22 AWG high-temp silicone 2 conductor wire, red/black ($18 for 82 feet)
  • 1 TE Connectivity Automotive connector male 1-1534155-1 ($0.62)
  • 2 TE Connectivity Automotive connector male pins 1-928918-1  ($11.60 for strip of 100)
  • 1 TE Connectivity Automotive connector male cover 1-1534027-1 ($0.43)
  • 1 TE Connectivity Automotive connector housing female 1-1534113-1 ($0.34)
  • 1 TE Connectivity Automotive connector female latching clip 1534112-1 ($0.64)
  • 2 TE Connectivity Automotive connector female terminals 5-928999-6 ($0.36 for 2)
  • 1 T-tap connectors ($12; package of 12)
  • 1 strip of grey supersuede or thin felt with adhesive backing – 9/16″ wide by 5 1/4″ ($11; for 36″ roll)

Trunk Light Kit Parts

Tools
  • Crimp tool or small long-nose pliers
  • Pliers (to close T-tap connector)
  • Wire stripper/cutter
  • Soldering iron and solder
  • Flat screwdriver (to pry Tesla LED module out)
TT 3D Printed Mounting Bracket

We designed a mounting bracket that protects both the car and the LED strip, and provides an adhesive-free mounting. It also looks great, but that’s a minor feature for this application. Download the STL file Model 3 Trunk LED V2

led bracket

Any 3D printer than has a heated bed should work to print this part.  For filament, we used HD Glass PETG in translucent black.  Other colors such as transparent or transparent white may work, but we did not try it.  Do not use PLA as it will deform under temperatures encountered in your car. ABS has an even higher temperature rating, but it can be more brittle and has some nasty fumes when making it. Printing was done at 300 μm layers, no support, and no raft. It consumes about 10 grams of material.  Your printer may require different settings depending on the filament you use.  For our printer, it took a little under an hour to print the part.

If you don’t have a printer, you can use 3Dhubs to find someone to make the bracket for you. A quick check appears it can be made for less than $15, depending on the quality. Ideally, you want a printer that doesn’t require a raft, but there is no way to specify that in 3Dhubs.

Assembly

Cut the wire into two sections, one 4″ long and the other 32″ long. On the 4″ section, strip about 1/16″ of the insulation off of each wire on each end. Tin each lead with a light amount of solder (optional).  The orientation is important!  Look at the image to orient the terminals (left) and the pins (right) with the black and red wires.  Use a crimping tool (if available) or use long-nose pliers crimp onto the wire. I elected to solder each wire as well (optional).

female connector

Female terminals with housing orientation, positive/red on smooth side of housing

 

male connection

Male pins with housing orientation

Insert the pins/terminals into the respective housings, be sure to use the correct polarity. On the male housing slide the locking clip cover onto the housing. On the female housing, slide the thin cover onto the housing. If the clip or cover is not installed properly, the connector will not fit!

With the 32″ remainder wire, remove 1/16″ insulation and solder to the end of the LED strip, connecting the red lead to the + and black to the – lead.  Use the T-connector to connect the other end of the 32″ wire to the center of the 4″ wire that has the connectors on it. Be sure to use the correct polarity.

T assembly

Completed connectors and T-tap

Testing

In the Model 3 trunk, remove the left side Tesla LED module. You can use a screwdriver to pry it out, as there is an indent on one side. It helps to press from the back of the LED module to pop it out. Remove the connector from the LED module – it has a retaining lock that must be depressed before the connector will release. Even with depressing the retaining lock, sometimes it requires a screwdriver to pry it out.

Temporally connect the your new TT LED assembly between the wire harness and the Tesla LED module.  Confirm the original Tesla LED module lights and the new module also lights up properly.

Problems

If one or both lights are not working, the polarity is likely wrong on one of your connections:

IssueSolution
Neither Tesla or your new TT LED assembly lightThe female connector is wired backwards
Only the TT LED assembly lightsThe male connector is wired backwards
Only the Tesla LED module lightsThe T-connector is installed backwards or the wires on the LED strip are backwards
Final Assembly

With working lights, slide the LED strip into the 3D printed plastic bracket. Route the wire out the side hole.

LED assembly

Assembly prior to backing

On the flip side, confirm the LED strip is centered in the bracket and adjust if necessary. Cut the grey Supersuede to size. Remove the backing tape and apply the back of the LED bracket. We added this to ensure there is no vibration noise and to seal up the assembly.

backing applied

Backing applied to bracket

Snap the TT LED assembly into the upper center trunk under black plastic cover. Route the wire behind the black cover over to the Tesla LED module hole and poke the wires with connectors out of the hole. Connect it to the wiring harness and the LED module.  Confirm it is working. Insert the Tesla LED module back into the opening so that it snaps into place.

trunk lighting

Looking upwards from trunk floor with the TT LED assembly installed

If you have the trunk open for an extended time, the LED power may be turned off by the car’s software. If this occurs, close the trunk and reopen it.

Results

We’re really pleased how much it improves the lighting!