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.

Good test run today. Got a brief video of the motors operating from the seat switches and when the door opens and closes.

Something to notice is how fast the motors move when tightening the side bolsters.

See Video



Here is a pic of a complete assembly
Attachment 130081

Great work!!! Did you wire the Active backrest width with the centre console switches? In the beginning you said that you will try not to wire them. How did you proceed?

Option 456 is required to be able to include this add-on option 4MF. You will still need to add the new modules and motors like I am doing.

I have not installed the switches yet and the motors are working from the seat buttons. What I have not been able to get is for the active backrest control to show up in iDrive. I will continue testing some programming options to see if I can get it to come up. If not, then I will install the switches and see what happens.

Some extra info on who makes the system:

http://www.newmaterials.com/Customis...orts_seats.asp

Complete success!

I have the passenger seat set fully installed and everything is working.

The buttons are required for this to work. I could not get an iDrive menu option to show up until I installed the switches. After I plugged in the switches and started the car, pressing the button causes the seat settings to display in iDrive for a few moments to show the selection. I'll get some more pics up another time.

Jim

Congratulations, that i was hoping to hear from you. The bad thing is that the seat is only active when you press the button. if it was active all the time i think it would be better. Great DIY. Could you post what is needed to be coded?

I can't say exactly as I had option 4MF coded for months before I had done some other coding for other projects. That said, I think it was just 4MF added to the FA and and an NCS expert default code of APPL, and maybe KOMBI. I never made any manual changes to get it working - just default expert code.

So here is the button and screen display:

Attachment 130130

Attachment 130129

Be sure to attach pop-tart cardboard to the seat rails to keep from scratching the car when removng the seat
Attachment 130134

Drilling out the pop-rivets that hold the original motor and slider mechanisms is really easy but be sure to catch ALL the metal pieces to keep them out of the seat moving parts amd leather covers. This is a pic looking at the side of the seat with the leather removed.
Attachment 130132


This pic shows the the slider part attached to the side bolster with hog rings. Pretty easy to reattach if you have hog ring pliers and hog rings
Attachment 130131

Be sure to account for all the metal bits when you remove the exisiting motor and sliders
Attachment 130133

A few final notes for this project:

- The coding is pretty simple - although I can't EXACTLY which steps were required. An update to the FA with 4MF and a code of the BGM, CAPPL, and KOMBI.
- The switches seemed to be required. No interface to the backrest settings without pressing the button.
- With the cables already made, this is a 1 day project
- Remove both seats. Seats are easiest to remove out the rear door with the rear seat out.
- Tap into the PT_CAN BUS and route pt_can_high, pt_can_low, 15wakeup to each area under the seats

Each Seat
- Open the leather side flap areas on the seat, remove rivets, remove hog rings attaching side bolster to drive mechanism
- Pull existing motor out the back
- Insert new motor into position but not all the way
- Attach motor plugs before inserting motor fully into position. It is hard to reach plugs afterwards.
- Route cable under seat
- Attach new module under seat and attach cables

- Install seat and attach pt_can_high, pt_can_low, 15wakeup
- 30amp power and gnd can be re-used from existing under seat connections

- Install new switches in dash console
- Code for option 4MF

Hello mate, can you please guide me where I am fitting a new seat from M5 which has active backrest and heating from factory. Mine was basic half electric seat.

Normally I ran a cable from SGM (K_CAN_SH/SL) to the seat X275/279 (yellow connector). There is an additional ground which I connected to the driver side 8 pin connector pin 2. Now when I try to use the buttons on my seat passenger side seat button activates driver side seat and vice versa.

Also what all cables are required is to be taken from KGM for backrest width adjustment to work? Aren't they on K_CAN? Any additional power to be fed? Can you please point me to the right direction?

Don't know how to edit the post above. This is how I have wired it:

Ran two cable for K_CAN from SGM to the 8 pin connector. Ran a cable for LIN bus (K_BUS) from yellow connector to the SGM, actually I reused the existing wiring which was there for the seat heating.

I'll write some more when I get a moment and not on my phone....

Both active backrest modules are the same. What determines whether it is a driver side or passenger side module is if an Extra pin is grounded or not.

Thanks, got the buttons sorted, grounded one is passenger I thought it was driver side hence the problem. Now switches are all sorted.

Regarding the active backrest width feature I will need to take 3 wires from the KGM (PT CAN HI/LO and WAKEUP) to the seat module. I don't know which pins of yellow plug they will go to, can you please help me there. Also what is function of WAKEUP line?

I can't get to my info on the Pinout just yet. The wakeup signal is what is used to turn on various modules once the ignition is switched on. They have power but are not "turned on".

Congrats!!

Just so your know ALBV_TOGGLE_APP is the function in CAPPL.
If you enable MDRIVE and MDRIVE_ALBV in CAPPL this should give you the seat adjustment menu.

I'm pretty sure I had the correct setting in CAPPL prior to installing the switches. It works like the seat heaters - there is no menu interface to change the seat temp until you press the button and for backrest there is no way to turn it on and select sport/comfort etc until the switch is pressed. On the other hand... I am turning on my backrest automatically when the car is started via my custom module in my miDrive project so one could do without the switches and integrate their control into something like that.



after having lived with this now for a while I can say I really like the Active Backrest. The seats react very quickly to changing conditions and provide a lot of support in the turns that you wouldn't otherwise have. For example, it may not be practical to have the side bolsters closed as small as they will go because it may be too tight for a lot of guys. With this setup, the seats are left open to a comfortable but supportive position and when a turn is taken the outside side bolster closes in fast and in stages to get progressively tighter the more aggresive the turn.

Ok, got it connected now.

Active backrest width adjustment will need PT CAN line as it gets its data directly from DSC which tighten the side bloster on turn. PT CAN line can be taken from KGM.
On X275 PIN 20 is WAKEUP line connect this to PIN 27 of KGM X16760
X16760 on KGM (first big connector from left) PIN 30 is PT_CAN_L and PIN 29 is PT_CAN_H and on X275/X279 PIN 16 PT_CAN_L and PIN 15 PT_CAN_H. Connected them togather.

Code SA4MA, SA456, SA4MF (only with active backrest width adjustment), all functional. Now I need to replace the switches and all done.



Side blosters are making cracking noise when tightening or opening, as if something is being tightened too much but it is very responsive. Haven't connected the passenger seat yet so don't know if both do it or it is just the driver side. Is this what you guys experiencing too? Is it normal or the active backrests are on their way out.

Glad to see you got it. My backrests make very little noise when moving. Just the sound of a motor whirring briefly.

This confirms new retrofitted seats have problem, not sure what exactly is making noise. Worth having a look? Is it easy to open the side blosters and see what drama is happening there?

You can get the seat backs off while the seats are in the car. From there you can see both motors and part of the gearing assembly that moves the bolsters.

NoQuarter, from this retrofit of yours do you remember if there was a difference in wiring between driver and passenger seat for the active backrest. Looking at my seat wiring it seems like these new seats I have installed have different wiring in the passenger side. Active backrest on the driver side takes power from PIN 25/24 as in this diagram and passenger side is like this diagram where they are powered by PIN 14/13.

At the moment connecting PT CAN lines to my passenger seat makes PT CAN line go dead. Everything on PT CAN line stalls including driver side blosters. This is just by connecting the wires to the passenger side and powering up the car, whole car behaves weirdly, like wipers going off and all sorts of error reported on the dash. Take the newly made connection to the passenger side out and all goes back to normal. This makes me believe active backrest module is fried on the passenger side. I want to swap passenger side control module to the driver side, do you know how to take out the control module (that black plastic box) for active backrest module A854 as given here.

The symptoms you describe with the wipers going off and such are similar to what happens if the wrong communications signal is patched into the canbus - so either you have kcan into pt-can for example OR the module is bad like you said. To remove the module you will need to take the seat out again to get it out from the bottom. it is held in place by a couple snap tabs that hold onto one of the cross-bars and a single screw. The catch is I don't know how to get to the screw short of removing the seat cusion. I installed my modules and couldn't get to the screw so used zip ties instead because I didn't want to remove the seat leather cover and cusion. But there may be another way I just couldn't figure it out not having seen one properly installed.

From the persepective of the seat harness, the wiring is identical with the exception of the extra ground to indicate passenger/driver side. Where power comes from the car would be different which is what you describe with pins 25/24 from the car and 14/13 from the car but they go to the exact same place on the seat module. Instead of trying to swap modules to test, can you run the drivers side wires over to the passenger module to see what happens?

Also, remember that canbus networks are a low-voltage, signal difference type communication protocol so the signal on the wire can be sensitive to interference. The wires must be twisted like a computer network twisted pair cable. If you made a fairly long run to get pt_can from under the dash to the seat perhaps you are getting a bad signal?

No quarter it seems like you know a lot about this stuff and I figure instead of starting a new thread id just jack yours. Reading your thread has made me want to change out my seats I have a US 530i 2004 just memory seats with lumbar adjustment. Suppose I could some how score a nice deal on some used comfort/active/sport/heated seats what would I need to do to get them retrofitted with all options working on my car I only have the dsc button so I suppose i gotta get a new button panel that supports all those features, but would the chairs be pnp if i transplanted them from a pre lci m5? Where should I start to make this dream a reality.

Nothing about it will be pnp but it can certainly be done. My first recommendation is for you to begin to understand how to read diagrams like the ones mentioned by Al001 in post # xxx above. This is what is required in order to learn where canbus signals like pt-can or k-can must go, power and ground of course, and so on. Find the diagrams for your existing model year and seats, print them out and take your existing seats out and track down the wires and satisfy yourself you understand how your seats work and how they connect to the car. This is exactly what I did for my seat project - took one out and learned how it worked, put it back then worked on my parts order and harness making.

Finally, you will need to be able to code your car to work with the new modules so you will want NCS Expert software, OBD cable and reading up on the various coding threads in this forum or at east track down a forum member that can code it for you.

thanks for the reply I was hoping it would be pnp im going to take a look at the wiring diagrams suggested . Its all in the if stage now, but i have seen an m5 at a local junk yard should I feel like this is something I can handle maybe I'll try it out but i must admit the wiring gets me nervous. as far as the coding goes I can probably handle that part as ive coded a few options on my car already with ncs

Update:

Good news, all functional now. No problem with the module. You were spot-on mate, it was my cabling. For some reason connecting PT_CAN line on the passenger side was simply making whole PT_CAN line go wrong, even with no module connected. When I connected the driver side module to the passenger side it was no different. Just to test it further when I connected my custom harness directly the module pins PT_CAN ws fine, this gave me hope. I still don't know why the hell a few extra centimeters of stock car harness will cause such PT_CAN to go dead.

Once PT_CAN line was sorted I thought I will check if the module responds to the tool32. I had driver side module disconnected. To my surprise passenger side module was only responding as driver side module and it took FLBV coding using NCS. Driver side bloster switch was controlling passenger side blosters. This made me happy in a way that atleast module isn't dead.

Part number of both the module were the same. Was wondering what distinguishes between them, found it was an extra ground (just like seat module) connected to pin 7 X11550, connected that as soon as realized and then passenger side BLBV module took coding and all was working as expected.

Long journey though but made there in the end. That bloody wiring investigation took a good portion of 1.5 days of hard labour, constantly marred by worry. btw. just to let you know I could not take the module off from driver seat, when I said I took the module off I meant I only took out the module circuit out of box which was much easier and (possibly only) way to take it out. Module is designed not to be taken out, all due to a screw between seat underside and module topside making it highly inaccessible, if not impossible. You can do it if you have right tools but I didn't. Definetely some bas**rd designed it, a stupid of high grade.

Cheers mate. All done and dusted now. Once wiring is investigated and fixed I will wrap all up and call it a day.

Great persistence on your part - well done! Please come back after a while and let us know what you think of the Active Backrest function. I thought it would be a cool project and the backrest somewhat of a gimmick but I really like it. I'll look you up again to make some progress on the Sport Automatic Trans upgrade.

Yes will report back soon. Still I need to figure out why is driver side so noisy.

Btw. do you lubricate/apply grease to the moving part of the seat? Perhaps driver side backrest motors lacking lubrication.

You can get to the gear part with the back seat cover removed. There is a clear snap on cover over the motor connection to the gear drive. Maybe something there will be evident.