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Passenger seat Lumbar support
- Thread starter MY_FTW
- Start date
Mike_TV
Active Member
Successful retrofit of passenger lumbar on 2021 Model Y
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...
teslamotorsclub.com
From the thread @Mike_TV linked, passenger lumbar is no longer supported in software, so retrofit using Tesla parts doesn't work.
Grandpa Gebis
Member
In theory it should be possible to leave the Tesla computers out of the equation and use your own controller - the actual hardware is simple. I don’t think anyones bothered thus far.
So digging into the wiring diagrams, I think it would be pretty feasible to use the factory switches. It appears the switches are relatively "dumb" so to speak - just outputs an "analog" signal to the body controller (left or right) for the lumbar switch and seat / backrest tilt switches (by "analog", I assume they mean that each direction would output a different resistance to ground). Body control module then sends a LIN-signal to the lumbar module to inflate/deflate the bladders.
Cleanest way to do this would be to remove the pin that goes from the lumbar button to the body control module, and wire that up to your own microcontroller setup (arduino or similar would do fine here). Then transmit the appropriate LIN signal to the lumbar module. That does require figuring out the LIN commands however.
Option B would be to eliminate the tesla lumbar module altogether and control the pump and bladder through your own mechanism (a few mosfets or something).
Sorry for the double post, but I think using the lumbar support pump/valve block from another car attached to the Tesla bladders might be the cleanest path here. The one I have in mind is the BMW F30 piece, but there may be other acceptable ones out there.
The BMW switch works similarly to the Tesla one in that the rocker connects outputs a different resistance to ground depending on which direction is pressed. I imagine the actual resistances are different than the Tesla switch, but that should be easy to work around. Unlike Tesla however, the valve body / motor electronics evaluate the difference resistances directly, rather than going through a body module and communicating over the LIN bus . So it really should just be a matter of connecting up power, ground and the switch.
The BMW valve body and pump look like they'd mount quite similarly to the Tesla bits (in fact the actual bladders themselves look very similar too, but would probably be best to just use the tesla bladders).
The BMW switch works similarly to the Tesla one in that the rocker connects outputs a different resistance to ground depending on which direction is pressed. I imagine the actual resistances are different than the Tesla switch, but that should be easy to work around. Unlike Tesla however, the valve body / motor electronics evaluate the difference resistances directly, rather than going through a body module and communicating over the LIN bus . So it really should just be a matter of connecting up power, ground and the switch.
The BMW valve body and pump look like they'd mount quite similarly to the Tesla bits (in fact the actual bladders themselves look very similar too, but would probably be best to just use the tesla bladders).
A2be
Member
Sorry for the double post, but I think using the lumbar support pump/valve block from another car attached to the Tesla bladders might be the cleanest path here. The one I have in mind is the BMW F30 piece, but there may be other acceptable ones out there.
The BMW switch works similarly to the Tesla one in that the rocker connects outputs a different resistance to ground depending on which direction is pressed. I imagine the actual resistances are different than the Tesla switch, but that should be easy to work around. Unlike Tesla however, the valve body / motor electronics evaluate the difference resistances directly, rather than going through a body module and communicating over the LIN bus . So it really should just be a matter of connecting up power, ground and the switch.
The BMW valve body and pump look like they'd mount quite similarly to the Tesla bits (in fact the actual bladders themselves look very similar too, but would probably be best to just use the tesla bladders).
That is an interesting idea.
Has anyone confirmed that the Tesla passenger seats currently being installed in Model 3/Model Y have the bladders already in the seat? ... and they just aren't hooked up?
A2be
Member
So I'm an older guy. Back when I was first building up an old car to drive from parts in the early 1970s, junkyards would specialize in carcasses of a few brands. When I wanted an old Mazda part for my car, I just showed up to the junkyard 20 miles from where I lived that had a lot of Mazdas, Subarus, Hondas, and Toyotas, and we'd walk out to a car, find the part I needed, and then negotiate with the junkyard man a price. Sometimes, I'd have to unbolt the part from the carcass myself.
So the QUESTION is: is anyone doing this for Tesla's today?
With 300k+ on the roads, crashes and such happen, I would think that the junkyards ought to be getting a lot of carcasses of Tesla Model 3s & Ys. From these, we could find seats with the (formerly standard) lumbar support, it would seem.
Bikeman
Member
Keep in mind that if anyone adds a 3rd party bladder and powered controler/pump and switch to the seat, that the Y's and 3's now are all 15.5v and not 12v. Maybe a bulb pump and bleeder valve could be a safer option?
In the case of the bmw module, their docs specifically state it’s rated for 12-16v
I plan to use the factory switch, and that doesn’t have a 12v power supply at all. Just a ground and the switch outputs (backrest, seat bottom, and lumbar)
Bikeman
Member
Georgesb2
George Borrelli
You can very easily add some padding where the lumbar support goes.
Remove the head rest. Pull off the back cover. Have a foam piece and insert between the yellow plastic and the white foam.
Let me know if you have any questions.
George Borrelli
Crystal River Florida
