If you have a Tesla Model 3 that’s not a 2021 build, you most likely don’t have an automatic trunk. Installing this can be a challenging DIY project – but it’s possible! You just need a few hours and a lot of patience. It also really helps if you have a partner to help you. The video above goes into great detail, but here is an outline of steps. 

Tools You Need 

  • T40 Torx bit
  • T25 Torx bit
  • 8mm Socket
  • 10mm Socket
  • 13mm Socket
  • Ratchet
  • 8mm Wrench
  • 6” impact extension 
  • Electrical Tape
  • Painter’s Tape
  • Drill
  • Pry tools (the kit does come with some)
  • Fish wire (the kit comes with a short one, but I prefer using a longer one for pulling leverage)
  • WD40 Silicone Lubricant 
  • Gloves
  • Flathead screwdriver
  • Floodlight/flashlight/headlight (a light you can use easily to see in the tight spaces)

Trunk Inside Liner 

-It’s only held by clips, so pop it out.

-Replace broken clips (if any).

-Connect latch cables in liftgate. 

-Install trunk button on the liner using the drill bit the kit comes with. 

-Put liner aside for now.

Trunk Disassembly 

-Remove rubber seal to right above bottom corners.

-Remove latch trim panel (connected by clips again).

-Underneath that, there are four clips to remove using pry tools.

-Remove bed liner.

-Remove top panel by taking out the two clips (one on each corner) and popping it out.

-Pull back the fabric on the side right underneath where that panel was, and disconnect the light with push tab (both sides). 

Bumper Disassembly 

-Unlatch electrical connection to the taillights. Make sure to unlatch the safety tab all the way.

-Remove the two 8mm bolts with a wrench. Hold the nuts so it doesn’t fall through. 

-Remove plastic bolts above lights.

-While holding the very top part of the light and the side, carefully pull the light toward you. You’ll hear the clips pop. Make sure to not pull upwards – only out toward you. 

PRO TIP: It’s a good idea to put frog or painter’s tape around the car panel on the sides where the bumper meets. This will keep it from scratching the car if something were to slip or rub against it during the process.

-Remove 3 clips around the bottom edge of the rear wheel well. 

-Remove the T25 Hex Screw at the top side of the bumper where the bumper meets the body panel. 

-On the back underside of the bumper, you’ll see two covers at the outermost part of the bumper. Unclip to reveal and remove two 10mm bolts. 

-Remove three more 10mm bolts that are further under the car. 

-Remove the two 10mm bolts for the area that covers the battery (even further under car). This makes it much easier to slide the rear bumper cover in later. 

NOTE: Do not remove the bolts on the side of the bumpers. This attaches the undercarriage and you DO NOT have to disassemble that. 

-Remove two more 10mm bolts on the headlight areas.

-Once all bolts have been removed, starting from the sides, pull the bumper out toward you. (It helps to have someone help during this process.) Work your way toward the middle from both sides. (Do not lose the little metal clip that comes out on the side of the bumper once you pull. This must be reinstalled with the metal clip facing upwards creating a volcano look.) 

-Once the bumper is off, be careful not to pull away immediately, because you need to unlatch and disconnect the sensor cables first. Place the bumper in a safe area. 

Strut Installation 

-Place a towel on the glass roof. This ensures that you don’t damage the area if something were to slip. 

-Using a flathead screwdriver, lightly pull away the latch to disconnect the old struts. Remove the top first, then the bottom. Make sure to store them in a safe place (or give them back to the customer) in case of any issues arising in the future. 

-It helps to have another person hold the liftgate up. It’s heavier than it looks.

-Get the new struts and inspect them to see if the “teeth” are aligned. If not aligned, it will be very difficult for it to go in. Once aligned, it should pop right in (we recommend bottom first, then top). If not, use the flathead screwdriver to pry back on the latch slightly so the teeth open up for more clearance. 

-Run the cables around the rubber seal and beneath the taillights. Continue running it down until you see a channel between the ultrasonic sensor bracket and the crash bar. There is a small blue or black rubber grommet attached to the bottom part of the trunk. Remove the rubber grommet and cut an X through it so the cables can go through (Or get a replacement). 

-Once the cables are running through the trunk area, you’re good to go. 

IMPORTANT: Make sure the cable has slack underneath the entrance point into the trunk. Create a loop that goes back up to the hole. This will ensure water won’t get into the trunk via that cable.

Fish Wire (Most Time Consuming Part of the Install) 

-There are two zip tie clips holding the rubber tube to the trunk. DO NOT BREAK THESE AS YOU WILL REUSE THEM. With a small pick, push the lock tab up and slide the zip tie out. This allows for more wiggle room while fishing the wire through.

-Gently take out the rubber seal on the top of the tube. Pull the rubber back, revealing a plastic clip. Depress the two clips on each side to remove it. 

-Gently take out the rubber seal on the bottom of the tube going into the car, revealing an opening that you will fish through.

-The button connector needs to be disassembled for it to go through smoothly. TAKE A PHOTO BEFORE DOING THIS NEXT PART. Use a small pick tool to get under the tabs and pry it to release the metal connectors. There are three wires to remove. 

-The other cable that needs to go through is for the latch. This one CANNOT be disassembled. 

-Using the fish wire provided, fold both of the cables into the loop. Massively tape everything (electric tape is best for sliding) at least 3-4 times around, because it could get damaged as it travels.
-PRO TIP: Make sure you run your cables below the trunk holes and through the right channels. If it’s behind the wrong areas, you may have to fish wire again. 

-Spray WD-40 Silicone Lubricant inside the tube. 

-Pull the fish wire through the tube as your partner shimmies the tube. This will help make it travel smoothly. If it’s stuck, make sure to inspect and feel the tube to make sure it’s not damaging anything. 

-Once out, pull it until you have enough cabling to reach the liftgate button area. Then, remove the tape and fish wire.

-Run your cables underneath the metal parts of the liftgate. 

-Connect fish wire cable that you put aside earlier.

-Reassemble the button connector. Use your picture reference! 

-Remove the two latch cables. One is rectangular and the other is circular. It goes into the Hansshow pigtails. 

-Once connected, use a zip tie to manage the cables. PRO TIP: The cables may get jumbled up in the center. Try not to manage your cables in the center where the clips are so that it doesn’t get stuck or messed up. So, tuck them towards the hole as much as possible. 

-Connect the button and put back the trunk liner. The best way to do this is to remove the white clips on the top sides and install them into the liner. Then, align the corners and push them in. Pull very hard and try to get the other white clips to attach. You may need help doing this part. Line up all the other areas and use your fist to push them all into place. Don’t miss pushing the middle one!

-Go back to the tube that you fished through and reinstall the top clip with the rubber seal as well as the bottom seal. Tighten the two zip ties back.

Power and CAN bus Installation 

-Make sure you install the ground cable FIRST. This can be installed on the passenger side of the trunk. There is a 10MM bolt. Do not remove the bolt. Just loosen it so you can slide the ground cable in under it. Tighten it once you have it in place. 

-Put the rear passenger seat down. 

-Remove the side panel next to the seat near the rubber seal by pulling it from the top. Be very careful. The clips CAN break easily. 

-Run the POWER and CAN bus cable through from the trunk. You’ll see a very thick tube that holds essential cables. Use a flashlight to see where you can run the cable alongside those cables that are already there. Get a friend to help you run the cable. You shouldn’t have to use a fish wire. Just have them pull as you push. You want to give yourself a lot of slack since you’ll be running the CAN bus to the center console. 

-IMPORTANT: Go to the front and POWER OFF the vehicle. (Settings > safety and security > power off)

-Unlatch the back seat and raise up. On the passenger side, you’ll see a black covering. Remove that.

-Unclip the high voltage latch. You don’t have to take it all the way off. 

-Attach the fuse to the cable.

-Run the ground underneath the red positive rubber seal to the connection to the 12V. Loosen the 13mm bolt on the positive terminal and slide under. Once the tap is on the terminal, retighten the bolt back. PRO TIP: Pushing the tap onto the terminal can be a little tight, so use needle nose pliers and grab the back of the tap to help push it onto the terminal.

-Now for the CAN bus, you’ll want to move your front passenger seat all the way forward and up, allowing for plenty of space for you to work. Make sure you don’t damage the visor mirror as you pull up!

-Remove the plastic side panel near the seats on the bottom. Run the two cables through that and under the side plastic liner all the way to the velcro part beside the front passenger seat. Use a pry tool to make it easier.

-Run the cable UNDER the seat tracks, tucking in excess under that velcro part. This is very important so it doesn’t damage the cable as the seat goes up and down.

-Remove the panel at the bottom of the center console in the back.

-Remove the CAN bus connection. Use the Hansshow pigtail to connect it. PRO TIP: The 2017-2019 have DIFFERENT CAN bus connections. It’s slightly smaller. Make sure you get the right model. 

-Tuck the CAN bus cables inside the hole and run the cables around the sides of the center console. Use a prying tool to tuck it in. Run the cable near the center console and UNDER the seat tracks. Connect with the other cable you ran there.

-Tuck in cables under the liner underneath the seat with the other cables that are already there. 

-Put the center console cover back. 

-You should have plenty of excess cabling where you connected the 12V. Use a zip tie to bundle the cables together and tuck it away from the 12V. Make sure to cut the zip tie short. 

-From the trunk, pull the power and CAN bus cable in case you have too much slack. Once you’re good, reconnect the high voltage and put the black cover back on. 

-Clip the bottom panel back on next to the seat, and put the seat back on. 

-To put back the side panel next to the seat, start from the bottom. In some cases, the metal could bend so it’ll be harder to latch. (Check the metal hook to make sure it’s not too bent.) Once the two latches are in place in the bottom, pull the piece towards the side of the car to get the side clip to align and attach. Once that’s in place, the top should fall into place. Ensure that it’s not too loose. 

Testing

-Unscrew the trunk latch. 

-Install the Hansshow trunk hook. You want to keep this pretty high so it can grab the latch. (Use the original screws for the Hansshow hook.) Don’t worry too much about aligning this yet. 

-Put the trunk rubber trim back.

Connect the left and right lights on the top of the trunk. 

-Connect the motor to the main board. The main board has instructions on it and it’s numbered so connect everything.

-Connect the left and right strut cables to the board. The cables should run on the back side of the trunk. 

-Connect the power and CAN bus to the board. Connect the loop around to the other main cables. This is important to provide power to the other cables. If it is set up correctly, the lights should turn on at this point and beep.

-Make sure the trunk rubber dampeners are all the way in (located on each side of the liftgate). You should only see one ring. 

-Manually close the trunk. Don’t close it all the way. You just want to make sure the trunk hook is aligned. From the inside, have your friend see if it is aligned. Once aligned, use a T40 to tighten it. Hold it up while screwing it in. (Remember, you want it higher up so it can really grab the latch.)

-Now it’s time for testing. 

-Hold the auto button you installed until you hear three consecutive beeps then let it go. That controls the speed, and typically you want it at the highest setting which will be three beeps. 

-Once it beeps to confirm the speed, push the button to test the trunk and make sure it works and latches correctly. Make sure to test it at least 3 times using the button and 3 times from the inside. 

Putting it all Together

-If the test went well, you’re ready to clean it all up. Start by undoing all of the main board cables you just attached.

-Using 3M double-sided tape or the tape provided, attach the motor for the hook on the left side of the trunk underneath the liner. There is a depression where you can place it without it showing a bump. Then, connect the trunk hook cable to the main board. 

-Run all of the top cables such as the left and right light cables across the top and down to the bottom of the trunk on the passenger side. This is where the main board will be. 

-Run all bottom cables along the bottom liner and to the right side as well.

-Put back the top plastic part of the trunk, making sure all top cables are tucked inside. It’s easiest if you use the rubber seal to hold it in place. Once you have it in place, put back the two plastic clips on either side. 

-Reattach all cable to main board like you did earlier.

-Put double-sided tape on the side of the main board that doesn’t have the instructions. Mount the board onto the metal box with the power facing downwards. Tuck all the remaining cables to the side. There is a lot of space there. It may be a good idea to zip tie all the cable together for a cleaner look. 

-Make sure the trunk rubber seal is securely back in place. Using a pry tool work the areas so every channel slides into place. The innermost channel should go over fabric and plastic seal, the next channel slides into the gap, and the outermost channel should slide down over the bumper making a nice seal.

-Once you’re good, put back the 4 clips along the bottom edge of the trunk. Then, put back the long plastic panel that goes over the trunk hook. You don’t necessarily have to dislodge the rubber seal again. Simply start from the middle, use the trunk hook to align and tuck it in. There are two clips on each end. Make sure to push down on those.

-Test again to make sure everything works. If not, think through your steps again and readjust things as needed, and try again.

Bumper Reassembly 

-Line the bumper up in the middle and push the tabs in going out to the sides. Make sure you reattach sensor cables before putting it back on.

-Once you have the middle clipped in, it should be much easier to align the sides.

-Put the 10mm bolt back where the tail lights are to put the bumper in place.

-Reattach the tail lights.

-Slide the undercarriage below the covering that connects to it.

-Put all 10mm bolts back in.

-Put the Torx 25 screw back in.

-Put all clips back into place.