Successful retrofit of passenger lumbar on 2021 Model Y

[EVer Hopeful]

Man this sucks!!! Just about to take delivery of a new model y and had convinced the wife I could get her passenger lumbar before ordering the car!! I’m in the shitter now

Just glue something black, round and plastic onto the side of the passenger seat and tell her it the lumbar control. Tell her to press it and feel the difference, but also tell her it's really really subtle and only smart people can feel it

 

[Sunvalleylaw]

Man this sucks!!! Just about to take delivery of a new model y and had convinced the wife I could get her passenger lumbar before ordering the car!! I’m in the shitter now

Yeah I agree it is a bummer. I want it for myself, as I have a compromised lower back with formerly blown discs, and want it for road trips when my wife takes her turns to drive. We road trip a lot. Hoping some work around emerges. The good news, which probably won’t get you completely out of the shitter, but can help a little, is there are a lot of good lumbar pillows that will provide the essential function, and look like they could be stored in one of the little storage bins you can tuck under the front passenger seat. I guess that is what I am planning to do now in the short run.

I may also look further into getting the parts for the car seat and wiring a control I can hide under the seat with some velcro. Such as we were talking about above in posts 172 and around there. It is going to be my daily driver, and once the lumbar support is set up in there, not likely anyone will mess with it, as my wife doesn’t mind it being there. So maybe you can still do one of those things.

 

[terranx]

So I'm looking into the feasibility of retrofitting lumbar while bypassing Tesla's electronics altogether. It seems feasible. My plan is to use the lumbar valve body/control unit from a non-Tesla car while reusing the Tesla pump and factory switch. The BMW F30 valve body/control unit looks to be a suitable candidate - there are probably others out there.

So to explain how things work on the Tesla - The seat control switches appear to be dumb with no active electronics. Just trigger different resistances back to the front body controller which then goes and triggers the various motors and lumbar ecu.

The lumbar ecu is connected to the body controller via lin bus. It has 3 air tubes, one for the pump, and then 2 for the air bladders (upper and lower). The other connections are power, ground, motor power, and a ground passthrough for the motor. Said lumbar ECU also has some internal valves and such that it controls. So the lumbar switch signals the main body ecu with a different resistance for whatever direction, and then the body ecu commands the lumbar ecu to go up, down, in, or out - and the lumbar ecu will engage motors and valves appropriately to perform said task.

As we all now, Tesla decided for some reason that we can't be allowed to retrofit lumbar back. So now we have to bypass the tesla electronics.

Enter the BMW F30 lumbar support:

You'll notice it actually looks quite similar to the Tesla getup. Two air bladders, a motor, and a valve body / ECU. Said valvebody/ ECU seems to have the same mounting style as the Tesla piece itself.

The big difference is that it doesn't need to talk to a master body controller to work. The lumbar switch is connected directly to the valve ECU (using a similar scheme of different resistances to trigger the direction). And then it triggers the motors and valves to replicate the functionality.

Currently my plan of attack is to buy just the valvebody/ECU (relatively cheap on eBay), hook it up to the tubes and motor of the tesla piece, and trigger it using the tesla switch. Basically it'd come down to repinning a couple things at the ECU end and then running a wire from the seat control switches to the lumbar plug.

Anticipated issues:

• It's highly likely that BMW and Tesla use different resistances for the different directions. This isn't insurmountable, just have to measure resistances and change resistors on the boards.
• I'm not sure if the +12v on the lumbar connector is still active. If it is, that makes life easier (though does probably means Tesla could **** us again in the future). Otherwise we'd have to find a switched 12v source elsewhere. Not insurmountable in theory, but would add some complexity.

But yeah, this seems feasible to me, so I'm going to order some parts. There are probably lumbar control pieces from other cars that would also work, but I'm most familiar with the BMW ecosystem and have access to those wiring diagrams, which is why I looked there.

Tesla diagrams for reference:

And the relevant BMW diagrams:

 

[zikronix]

we know 12v comes to the tesla switch to move the other componets in the seat. couldnt you just cut the trace to the lumbar button then pull the 12v from the board its self to the lumbar portion of the switch?

 

[terranx]

we know 12v comes to the tesla switch to move the other componets in the seat. couldnt you just cut the trace to the lumbar button then pull the 12v from the board its self to the lumbar portion of the switch?

12v doesn’t go to the switch.

 

[zikronix]

12v doesn’t go to the switch.

oh i figured it did because the other functions work. I guess your post makes more sense now.

 

[terranx]

Yeah I've got it 95% figured out. Should be able to pick up my switch and lumbar stuff from Tesla tomorrow. My BMW module is already in, and I've got the wiring figured out for that. On the off chance the resistors on the Tesla switch are similar to the BMW switch, I might be able to get this done tomorrow itself. Otherwise maybe a little longer while I figure out how to modify the circuit inside the Tesla switch.

 

[gleearch]

Yeah I've got it 95% figured out. Should be able to pick up my switch and lumbar stuff from Tesla tomorrow. My BMW module is already in, and I've got the wiring figured out for that. On the off chance the resistors on the Tesla switch are similar to the BMW switch, I might be able to get this done tomorrow itself. Otherwise maybe a little longer while I figure out how to modify the circuit inside the Tesla switch.

It would be great if you get it to work.
Please post photos and your process. While it would suck for me to dismantle my retrofit and have to redo, it's better than having it totally bricked by Tesla in their infinite wisdom. I'm not on Twitter but since Elon is focused on improving service, I'm wondering if this is a subject he could revisit or at least have Service Centers provide the service to get the retrofits working again.

 

[terranx]

It would be great if you get it to work.
Please post photos and your process. While it would suck for me to dismantle my retrofit and have to redo, it's better than having it totally bricked by Tesla in their infinite wisdom. I'm not on Twitter but since Elon is focused on improving service, I'm wondering if this is a subject he could revisit or at least have Service Centers provide the service to get the retrofits working again.

Got my parts in from Tesla. Good news is the tubes fit the BMW module perfectly and the plastic mount is identical to the Tesla module. Power also seems to still be present at the Tesla harness, so don't have to go too crazy with the wiring (unless Tesla decides to disable power to that harness in the future, in which case a separate 12v source would be needed).

The seat switch as expected does have different resistor values than the BMW switch. I'll have to study the circuit a little bit to figure out which resistors to change, but it should be doable.

Now one minor complication might be that the Tesla lumbar switch seems to allow the buttons to be pressed in diagonals while the BMW switch limits you to the 4 directions. I don't think this is a huge issue (the way the resistances seem to be setup, the BMW modules would likely evaluate diagonals as the forward/backward directions), but might result in subtly different behavior than the factory setup.

Will try to post detailed steps once I'm ready to complete this

 

[ludicolo]

OK, I got my passenger lumber reactivated. The Tesla Rangers don't appear to have sufficient privs to change the gateway configuration, so I would talk to Tesla independent service facilities if they offer this. My understanding is the toolbox that independents get access to can put the car in service mode, then an ethernet cable to the MCU to edit the gateway config and request a firmware redeploy. I actually got matrix headlights and radar retrofitted to my late 2021 build Y as well this way. It was pretty wild, my avatar changed when the headlights did.

 

[zikronix]

OK, I got my passenger lumber reactivated. The Tesla Rangers don't appear to have sufficient privs to change the gateway configuration, so I would talk to Tesla independent service facilities if they offer this. My understanding is the toolbox that independents get access to can put the car in service mode, then an ethernet cable to the MCU to edit the gateway config and request a firmware redeploy. I actually got matrix headlights and radar retrofitted to my late 2021 build Y as well this way. It was pretty wild, my avatar changed when the headlights did.

interesting, I know for a fact that the service centers can do this because of the ecu update.

 

[generalmilk]

OK, I got my passenger lumber reactivated. The Tesla Rangers don't appear to have sufficient privs to change the gateway configuration, so I would talk to Tesla independent service facilities if they offer this. My understanding is the toolbox that independents get access to can put the car in service mode, then an ethernet cable to the MCU to edit the gateway config and request a firmware redeploy. I actually got matrix headlights and radar retrofitted to my late 2021 build Y as well this way. It was pretty wild, my avatar changed when the headlights did.

Radar will soon become dead weight though…

 

[ludicolo]

interesting, I know for a fact that the service centers can do this because of the ecu update.

Service centers might have more privileges than rangers in the field.

 

[Grandpa Gebis]

OK, I got my passenger lumber reactivated. The Tesla Rangers don't appear to have sufficient privs to change the gateway configuration, so I would talk to Tesla independent service facilities if they offer this. My understanding is the toolbox that independents get access to can put the car in service mode, then an ethernet cable to the MCU to edit the gateway config and request a firmware redeploy. I actually got matrix headlights and radar retrofitted to my late 2021 build Y as well this way. It was pretty wild, my avatar changed when the headlights did.

So you got yours reactivated via a third party with access to Toolbox?

 

[ludicolo]

Yes

So you got yours reactivated via a third party with access to Toolbox?

Yes, but toolbox was only used to put the car in service mode, as far as I can tell. Direct ethernet to the MCU to update the gateway configuration and trigger a firmware redeploy, which also updates all the modules including the passenger lumbar.

 

[ludicolo]

Radar will soon become dead weight though…

Sure, but the bumper was off anyway for the matrix lights.

 

[generalmilk]

Sure, but the bumper was off anyway for the matrix lights.

Did you bought these parts from tesla and retrofitted yourself?

 

[ludicolo]

Did you bought these parts from tesla and retrofitted yourself?

I retrofitted the lumbar which worked for a while before an update (gateway uses the vehicle config to figure out which modules to update, since passenger lumbar was not in original config, it doesn't get updated and the domain controllers ignore LIN messages from out of date devices).

Headlights and radar went in with the indy shop who did the software configuration and provided the hardware. I'm sorry I can't share more info because I'm not sure this shop wants to advertise that they do this work.

 

[terranx]

Of course all this comes out as I'm about to retrofit an alternate module and do some wiring (reversible, but still)

I understand not wanting to reveal the shop, but could you reveal a little more detail? Are they using the same Toolbox we can subscribe to here? And if so what's their method for changing the gateway configuration? Seems like tons of people have tried getting this retrofit and others and ran into roadblocks with the gateway stuff

 

[gleearch]

I know the independent shop wants to ensure they have business but it would be helpful if we understood how they did it.

interesting, I know for a fact that the service centers can do this because of the ecu update.

Were you able to get the service center to reactivate your lumbar controls? If so, what exactly did you have to do or say to get them to reactivate it?