[Imuboys]

Hi, I recently bought a full leather interior for my BMW e90 and the set that I got have seat heating and lumbar adjustment. My original seats had only heating and no lumbar adjustment and I would like to make it work since right now only the seat heating works. Dose anyone know what do I need to do in order for the lumbar adjustment to work?

[krhodes1]

Originally Posted by Imuboys

Hi, I recently bought a full leather interior for my BMW e90 and the set that I got have seat heating and lumbar adjustment. My original seats had only heating and no lumbar adjustment and I would like to make it work since right now only the seat heating works. Dose anyone know what do I need to do in order for the lumbar adjustment to work?

All it needs is power and ground. BUT, BMW in their infinite wisdom gave the lumbar support pump a different power connection than the rest of the seat, and if the car didn't come with lumbar, that connection is not on the car side of the seat harness. When I retrofitted them to my 128i seats, I just spliced the power wires on the seat side of the harness together. Could not for the life of me figure out why it wasn't working after I finished, took some deep study of the wiring diagrams to figure it out. I figure as long as I don't try to run the lumbar pump and move the seat at the same time it should never be an issue.

For anyone contemplating retrofitting rather than swapping seats, the seat trims have the hole for the lumbar switch half-cut from the back, easy to finish cutting it out, and the mounts for the switch is already there too. I got all the parts to do both seat for $100 or so used. Pads, wiring harness, and switches.

[Imuboys]

Originally Posted by krhodes1

All it needs is power and ground. BUT, BMW in their infinite wisdom gave the lumbar support pump a different power connection than the rest of the seat, and if the car didn't come with lumbar, that connection is not on the car side of the seat harness. When I retrofitted them to my 128i seats, I just spliced the power wires on the seat side of the harness together. Could not for the life of me figure out why it wasn't working after I finished, took some deep study of the wiring diagrams to figure it out. I figure as long as I don't try to run the lumbar pump and move the seat at the same time it should never be an issue.

For anyone contemplating retrofitting rather than swapping seats, the seat trims have the hole for the lumbar switch half-cut from the back, easy to finish cutting it out, and the mounts for the switch is already there too. I got all the parts to do both seat for $100 or so used. Pads, wiring harness, and switches.

Do you have any specific wires that I need to splice or any diagram in order to make them work? I searched on the internet for some info and I wasn’t successful.

[ptpending]

Originally Posted by Imuboys

Do you have any specific wires that I need to splice or any diagram in order to make them work? I searched on the internet for some info and I wasn’t successful.

search on this forum, i has few topics about this hack

[krhodes1]

Originally Posted by Imuboys

Do you have any specific wires that I need to splice or any diagram in order to make them work? I searched on the internet for some info and I wasn’t successful.

Sorry, I don't have any handy. I used the old online info site that got taken down since. You could make a new post asking for them, someone will post them for you.

[Imuboys]

Originally Posted by krhodes1

Sorry, I don't have any handy. I used the old online info site that got taken down since. You could make a new post asking for them, someone will post them for you.

I managed to find them in a YouTube video, fi anyone needs the link to the harnes diagram just ask

[pedro2u]

I swapped the seats in my e92 335xi and rewired it this link. Includes wire connector info

https://zpost.com/forums/showthread.php?t=1637489

[StradaRedlands]

Originally Posted by Imuboys

Do you have any specific wires that I need to splice or any diagram in order to make them work? I searched on the internet for some info and I wasn’t successful.

This is a generalization, but I hope it helps. Look at this diagram to get an idea:
https://zpost.com/forums/showpost.ph...60&postcount=4

Basically all seats will will have wire#4 as positive for the seat. But seats with lumber will also have wire #7 or #9 for the lumbar. Depending on the age of the seats, you'll need to jump that 7 or 9 wire to the 4 wire. Very easy job, either do it properly with a soldered on terminal, or use a fast clip sort of jumper to do it.

You might need to do the same with a ground wire as well, I don't recall doing that???

Here is my very low quality job that I'm not happy with, but it works fine:

[Imuboys]

Originally Posted by StradaRedlands

This is a generalization, but I hope it helps. Look at this diagram to get an idea:
https://zpost.com/forums/showpost.php?p=25071760&postcount=4

Basically all seats will will have wire#4 as positive for the seat. But seats with lumber will also have wire #7 or #9 for the lumbar. Depending on the age of the seats, you'll need to jump that 7 or 9 wire to the 4 wire. Very easy job, either do it properly with a soldered on terminal, or use a fast clip sort of jumper to do it.

You might need to do the same with a ground wire as well, I don't recall doing that???

Here is my very low quality job that I'm not happy with, but it works fine:

Thank you so much for the clarification, this is much easyer then what I wanted to do initially. I’ll probabil try to do it in the next couple of days.

[StradaRedlands]

Originally Posted by Imuboys

Thank you so much for the clarification, this is much easyer then what I wanted to do initially. I’ll probabil try to do it in the next couple of days.

Great, glad it helped. It's a straightforward job once you figure out what you need to do