Project: Active Backrest Retrofit


See the teaser thread here: http://forums.5serie...s-next-project/

Active Backrest is an option for the Comfort Seats where the backrest can be set with a Comfort, Normal, and Sport mode
It was only available with option 456 (Comfort Seat) and was not available with 455 (Active Seats - this is the one that massages your bottom)

I have only seen evidence of it exisiting in M5s but if anyone has actually seen it in anything else please let me know.

So what does it do?
Active Backrest monitors the DSC information and automatically adjusts the backrest on the outside of the turn to tighten up and support the driver/passenger during cornering.

The new buttons shown below. I will first do the install without installing the buttons to see that it can be made to work without the expense of the new buttons. I expect it can be controlled completely through the iDrive controller.
https://pfhw3a.dm2301.livefilestore....&cropmode=none

My seat on the bench. It is backin the car now, just took it out to inspect.
https://mpuddq.dm2301.livefilestore....&cropmode=none

Some of the controller connections
https://zky1xw.dm2301.livefilestore....&cropmode=none

The exisitng backrest motor that needs to be replaced
https://nqqrrw.dm2301.livefilestore....&cropmode=none

My test jig. What you see here is 2 motors for 1 seat - left side and right side. I plan to modify the jig to mount the other 2 motors to represnt both driver and passenger seats during testing
https://ytcojq.dm2301.livefilestore....&cropmode=none

The plan:
1) Create the cable harnesses for the seat
2) Create or update the harness from the car
3) Connect Jig to car - code the car - test jig operation during a drive
4) Remove seats again. Remove existing motor from seat. Install 2 new motors per seat with new wire harness. Install seats

I will consider making additional harnesses in the process that I will make available to purchase if it looks like there is interest.

The parts for this retrofit cost about $900USD and I can provide the retrofit harness (assuming I get all this to work!).

I will wait before I am ready to declare the price of the retrofit harness until it is done. Each retrofit kit requires ~100 connections to be made depending on the availability of compatible plugs to mate with exisitng plugs. If I can't find a mate then I will have to remove existing plugs and replace them also.

Not sure how this retrofit $ compares to the original option price but if you like your exisitng seats this is better than swapping out the whole seat for M5 seats.

Cool project. Keep us updated!! :twoup:

Update: This project is still in progress. I let it wait a while longer to do as a winter project.


Working on the seat harness at the moment but still have some parts on back-order. no delivery date yet :(

Good Luck! Can't wait to see how it turns out! :thumbsup:

Updates:

- The wire harness is 99% complete. Just the final connections to make between the seat controller and the car power and pt_can bus.

Harness bundle.
Attachment 129925

This pic shows the plug removed from the Body Gateway Module with pics removed for pt_can and 15wake-up
Attachment 129926

My adapters for connecting to pt_can and 15wake-up
Attachment 129927

Plugs wrapped up with tape
Attachment 129928


My adapter pins inserted back into the BGM plug
Attachment 129929

All wrapped up.
Attachment 129923


Attached back to BGM
Attachment 129924

pff ,thats easy
even a cave man can do it

the only problem ..is...there is no more cave man ALIVE :)))
looking to see the final results..
:)

Hi, is there any coding necessary to get everything working? Or it`s just plug&play?

It is just like any other option that is added to the car as a retrofit. it will require coding for the new modules to be recognized and for the interface to display on the iDrive screen.

Great DIY write up! Congrats on your progress!

I just checked my 06 option list and see that I have option 456 installed (full electric comfort seats), If I where interested in doing this retrofit, would I need to do the exact same thing you are doing, or is it just a case of coding in my case?

Looking forward in your reply.

Keep up the good work!

I'm not sure about the year - would need to double-check that the seat is the same part numbers.
You would need to do what I am doing.