Hi all,
I wanted to jot down quickly some notes on my successful passenger lumbar retrofit. I will edit with more details after I get some sleep. All in all, it took about an hour for me to figure out and take things apart and put them back together.
Decontented Model Ys have a the lumbar support frame and harness but lack the switch, pump, and control unit.
I started with a 2020 Model 3 seat that I found on Craigslist for $100, and my original intention was to just swap the seats over. However, I had heard that the harness for the lumbar is still in place in the latest build Model Ys so I thought I'd try to retrofit first, as it's a lot less work, and my Y had slightly nicer seat switch trim with silver accents.
What you need:
Tools: Torx T15, 10mm socket, a plastic pry tool or even like a disposable chopstick would be fine (for pushing on the clip for the headrests), a trim tool (looks like a small flat crowbar with a notch cut out of it)
1. Lumbar assembly from Model 3 or Model Y, looks like this: (apologies for bad photo, was quickly taking pics as I went along)
Make sure it includes the actual pump which has the red, green, and blue lines coming from it.
2. Passenger seat switch assembly with lumbar button. Does not need to match the model Y trim as you will be reusing the actual buttons except for lumbar from your Y. You also will not need the physical buttons except for lumbar for the same reason. The switch in your car does not have the contacts under the blank for a switch, hence your need for a replacement. Note that 2021 seat controls have a small silver edge on the buttons. You will reuse the cushion buttons but the lumbar will come from your replacement switch so it will not match the driver's side unless you get a switch from a 2021. You probably don't care, but worth noting.
Steps to remove lumbar.
1. Raise your headrests. If you push down on the trim around your headrest posts you will see two clips that you push to the left to release the post, you will have to move the post up a little to keep it from clipping back in. This YouTube video shows the procedure:
The service manual also has the procedure. They do not have to be fully removed, just mostly up.
2. Remove the backrest trim. I just put my hands behind the top of the trim and pulled gently. If it is not coming out pull up the headrests more, as they old in the trim on the top. It is hooked in the bottom a pair of plastic hooks, so just hinge the trim back and lift out and set down. The bottom fabric flap is held in by elastic straps that are a pain to reach so I did not bother unclipping. You won't need to for acces.
3. On the back of the seat you will see the yellow lumbar frame. Our seats simply have the inflatable cushions and pump removed, there is no additional padding to make up for it, but the frame makes this effectively a seat with lumbar set to minimum.
4. On the bottom of the frame you will see a single center 10mm bolt. Before removing, you'll see an elastic clip of fabric around the bolt. Lift and unclip the fabric, then undo the bolt.
5. On the left, the recliner motor connector needs to be disconnected, there is a release on the back of the connector that you can squeeze and the connector should just pull out. The harness for this motor also has two other connectors that are not connected to anything. A larger two row control unit connector and a four pin pump connector. The harness is clipped into the lumbar frame in two points. Use your trim tool to disconnect the clips from the frame. It is held in on both sides so simply get the tool under the clip and rotate it clockwise and counter clockwise and it will release.
6. Lift the lumbar frame towards the top of the seat so that the bottom clears the metal frame of the seat, then pull the lower part of the frame out and down to get it out. This is obvious once you see how the frame is mounted. You may need to press on the padding to get the frame to move.
7. Take your complete lumbar assembly and install it. connect the pump and control unit and the recliner, but do not clip the harness into the frame yet. the pump just fits into the empty space in the right bolster.
8.Raise your seat and move it forward enough to expose the T15 bolt you can see underneath the front right corner of the seat. Remove the bolt. Then pull the lower and upper cushion seat controls straight out from the switch. You may need to use a plastic trim removal tool to get under the switches to gently pry all around to get them to release.
9. Gently tug on the front corner of the seat trim, it should release, and the trim is also clipped in behind so as you tug it should come off as well. There is no need to disconnect the seat belt from the pretensioner on the seat, which you may have seen in the service manual.
10. From the back of the switch assembly pull out the harness. Connect the harness to the new switch you acquired and confirm the lumbar support works. Make sure the car is powered on (screen is on) as lumbar will not operate otherwise, even though the seat will. Disconnect the harness for now.
11. Remove the 3 Torx T15 screws holding in the old switch assembly and replace with the new, reuse your screws to secure them. Reattach harness and switch buttons and confirm operation. Reinstall seat trim and the screw in front from underneath.
12. Reattach the harness to the lumbar frame and take the seat back and reinstall it by hooking in on the bottom first (you may need to pull outwards on the cover at the bottom to clear the hinges) and then snapping in on top. Lower headrest all the way and you are done!
I wanted to jot down quickly some notes on my successful passenger lumbar retrofit. I will edit with more details after I get some sleep. All in all, it took about an hour for me to figure out and take things apart and put them back together.
Decontented Model Ys have a the lumbar support frame and harness but lack the switch, pump, and control unit.
What you need:
Tools: Torx T15, 10mm socket, a plastic pry tool or even like a disposable chopstick would be fine (for pushing on the clip for the headrests), a trim tool (looks like a small flat crowbar with a notch cut out of it)
1. Lumbar assembly from Model 3 or Model Y, looks like this: (apologies for bad photo, was quickly taking pics as I went along)
Make sure it includes the actual pump which has the red, green, and blue lines coming from it.
2. Passenger seat switch assembly with lumbar button. Does not need to match the model Y trim as you will be reusing the actual buttons except for lumbar from your Y. You also will not need the physical buttons except for lumbar for the same reason. The switch in your car does not have the contacts under the blank for a switch, hence your need for a replacement. Note that 2021 seat controls have a small silver edge on the buttons. You will reuse the cushion buttons but the lumbar will come from your replacement switch so it will not match the driver's side unless you get a switch from a 2021. You probably don't care, but worth noting.
Steps to remove lumbar.
1. Raise your headrests. If you push down on the trim around your headrest posts you will see two clips that you push to the left to release the post, you will have to move the post up a little to keep it from clipping back in. This YouTube video shows the procedure:
2. Remove the backrest trim. I just put my hands behind the top of the trim and pulled gently. If it is not coming out pull up the headrests more, as they old in the trim on the top. It is hooked in the bottom a pair of plastic hooks, so just hinge the trim back and lift out and set down. The bottom fabric flap is held in by elastic straps that are a pain to reach so I did not bother unclipping. You won't need to for acces.
3. On the back of the seat you will see the yellow lumbar frame. Our seats simply have the inflatable cushions and pump removed, there is no additional padding to make up for it, but the frame makes this effectively a seat with lumbar set to minimum.
4. On the bottom of the frame you will see a single center 10mm bolt. Before removing, you'll see an elastic clip of fabric around the bolt. Lift and unclip the fabric, then undo the bolt.
5. On the left, the recliner motor connector needs to be disconnected, there is a release on the back of the connector that you can squeeze and the connector should just pull out. The harness for this motor also has two other connectors that are not connected to anything. A larger two row control unit connector and a four pin pump connector. The harness is clipped into the lumbar frame in two points. Use your trim tool to disconnect the clips from the frame. It is held in on both sides so simply get the tool under the clip and rotate it clockwise and counter clockwise and it will release.
6. Lift the lumbar frame towards the top of the seat so that the bottom clears the metal frame of the seat, then pull the lower part of the frame out and down to get it out. This is obvious once you see how the frame is mounted. You may need to press on the padding to get the frame to move.
7. Take your complete lumbar assembly and install it. connect the pump and control unit and the recliner, but do not clip the harness into the frame yet. the pump just fits into the empty space in the right bolster.
8.Raise your seat and move it forward enough to expose the T15 bolt you can see underneath the front right corner of the seat. Remove the bolt. Then pull the lower and upper cushion seat controls straight out from the switch. You may need to use a plastic trim removal tool to get under the switches to gently pry all around to get them to release.
9. Gently tug on the front corner of the seat trim, it should release, and the trim is also clipped in behind so as you tug it should come off as well. There is no need to disconnect the seat belt from the pretensioner on the seat, which you may have seen in the service manual.
10. From the back of the switch assembly pull out the harness. Connect the harness to the new switch you acquired and confirm the lumbar support works. Make sure the car is powered on (screen is on) as lumbar will not operate otherwise, even though the seat will. Disconnect the harness for now.
11. Remove the 3 Torx T15 screws holding in the old switch assembly and replace with the new, reuse your screws to secure them. Reattach harness and switch buttons and confirm operation. Reinstall seat trim and the screw in front from underneath.
12. Reattach the harness to the lumbar frame and take the seat back and reinstall it by hooking in on the bottom first (you may need to pull outwards on the cover at the bottom to clear the hinges) and then snapping in on top. Lower headrest all the way and you are done!
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