maxseguin

kd7iwp

So I just took a look. There's a black connector on the module under the seat (not referring to the button pad) that has a red, brown, and yellow/black twisted pair coming into it and those wires come directly from the vehicle. Red (pin 7) is +12v, brown (pin 8) is ground, and the 5/6 twisted pair of black and yellow is the k-line (I believe, I know it's data, can't remember if it's CAN bus or K bus). Those power the module under the seat, however, just having that plugged in does not power up the seat as when I disconnect the large yellow connector (x275) the seat buttons do not work.

In the large yellow (x275) connector there is +12 volts at pin 25 and ground at pin 24. The remainder of the pins are all different data lines and safety system lines, as far as I'm aware.

kd7iwp

Ignore the wires coming out of the pink ethernet cord as I added those for my active backrest width adjustment retrofit.

maxseguin

seems to be okay for the black connector on the module! i don't have pin 24 and 25 on the x275.. im left with pin 2 (white/red with yellow lines) pin 3 (red/brown) pin 11 (brown) pin 12 (purple) pin 19 (white/red) and pin 23 (brown/black)

kd7iwp

That sounds about right. When I added the active backrest width adjustment I also had to put them in x275 to send power to the additional module under the seat, so that makes sense you wouldn't have those on 24 and 25. You can also ignore the blue/blue-red wires as those are a twisted pair of powertrain can bus for the additional feature as well.

maxseguin

so how should i wire this mess ahaha seems like m missing something or im wrong? i'm actually lost about the fact that the controller needs to speak to the computer...

kd7iwp

Unfortunately I don't know how to help there. If the seat feels it needs to talk to the rest of the car to operate, then that's just the way they made it. All the things are very interconnected in these cars. It communicates to do seat memory, heating, ventilating, side bolster adjustment (if you have the special seats for it), etc. The module underneath the seat is the brain of the seat, not the button pad on the side. Somehow we need to convince that module under the seat to turn on.

maxseguin

i found this guy that did a retrofit and he did bypass it in some way but i need some explanation or could just help in general

(I recently retrofitted my seats from half electric to comfort seats.
I got 3 errors on the dash, 2 of them are about head restraint pretensioners, old seats did not have them, so I had to run wires from drivers and passenger seats to B-pillar. the third error is restraint system, and it says "resistance too low".
I have used 16 amp wires instead of 5 amp, I am not sure if that could cause the difference.
there are two corners I cut:
first one is K_bus wire (#2 in yellow connector), I connected the wire to center console DSC switch instead running wire to the module behind the fuse box in glows compartment which is anyway connected to the DSC switch.
second shortcut, I run red/green wire (#3 in yellow connector) to the continuous 12V supply from seat supply wire (red 30 amps fuse). By the WDS it should go to relay in the boot connected to 5 amp fuse.
Relay supply continuous 12V too but only when the car is awake, when it goes to sleep mode it cut off.)

maxseguin

just came back from the junk yard with 2 different switch module and one is from the donor car which the module had no yellow and black wire

on a 2007 525xi i found another module but it has the wires!




on a 2007 525xi i found another module but it has the wires!
right here

kd7iwp

It's very possible that on the 2007 (pre-facelift) models that the center console unit is embedded in that switch panel. In the facelift versions they likely put the module somewhere inside the dash and then the buttons connect directly to it.

The information you pasted above doesn't necessarily mean that the seats will work when plugged into a DTC switch. There is a body module (I think, forget the name) behind the dashboard that controls the can bus network for body modules, like the seats and center console switches. It is also the unit that sends a message to wake up all the controllers on the network. Usually there are 2 communication lines and an additional "wakeup" line. The controllers all go to sleep when the car is off to conserve the battery and when you turn on the car a message (perhaps a few volts or something) is sent over the wakeup line that tells the module to start communicating on the bus. It's possible that you don't need the can bus hooked up but may need to have the wakeup signal connected, I'm not sure. I remember reading once about someone who had retrofitted F10 seats into an E90 or something and they had to build a little controller that sent a signal every few seconds to keep the seat awake.

Here's a wiring diagram for that x275 connector, some of it might be useful. A157 is a module in the B pillar used for the airbags, so probably not important. A169 is the center console switch module. G34a is also for airbags and safety systems. S50 should be the button panel on the side of the seat. S58a is also for the safety systems.