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Thread: 540 sport seat swap into 525ix - guidance please

  1. #1
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    540 sport seat swap into 525ix - guidance please

    Hey everyone,

    Been ages since I posted here, busy with life but now I have a chance to tinker on the cars again.

    I have searched the forums and web for some guidance and come up short on this - hoping someone can help me. I have a set of nice buffalo leather sport seats with memory and thigh support from a 95 540i. Donor car is long gone so can’t get any harnesses from it. The transplant car is a 95 Alpina B10 3.0 Allrad that came with manual seats. The harnesses are under the driver and passenger seats but do nothing when connected. They both have just a handful of pins present out of the 12 in the (I think) x603 connector.

    Long story short, the only way I can figure out to make this swap happen is to provide power and ground to the appropriate pins on the seat controller. Does this sound reasonable? If so, could someone aid me in figuring out which pins on the controller require power and ground? The ETM confuses me to be honest and I can’t figure it out.

    Here is a pic of the seat controller with the associated harnesses.

    FC6A4DF3-56E9-4BA1-913C-57EA52D4CAAE.jpg

    Many thanks in advance,

    Rob

    The kids:
    Alpinas: 91 E34 B10 Biturbo; 91 E32 B12 5.0; 91 E34 B10 3.0 Allrad (mom's car); '91 B10 3.5
    Bimmers: 91 E31 850; 93 E34 525i w/ aftermarket turbo; '01 X5 4.4; 93 E31 850i Dinan TT; 89 E32 750il Dinan TT; 92 750il w/ S70 engine and transmission
    Mercedes: 92 600sel; 93 S600 Lorinser
    VW: 04 Jetta GLS TDI

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    I'm currently stranded on Vancouver Island facing ferry after cancelled ferry, but when I get home I'll look at my spare memory seats and see what's what. Meanwhile... the ETM seems to imply that the body harnesses are different between cars with and without memory. Looks like most of the memory system is self-contained, and that the only new wires to run would be for mirrors. If you don't care about those, this should suffice, on paper:

    A X18319 18 pins black
    B X18320 26 pins natural
    C X18321 10 pins black
    D X18322 26 pins black
    E X18323 4 pins black

    Constant power to E/2 (2.5 red/yellow) from F42 (30A rear)
    Run/start power to B/2 (0.5 green/black) from F16 (30A front)
    Acc/run/start power to B/3 (0.5 purple/white) from F18 (15A front)
    Ground to E/1 (2.5 brown) and E/4 (0.75 brown/orange)
    Also, D/12 may or may not need to be grounded for the system to work.

    Post what wires you do have, which are ground, and in what key position any of them are hot. I'm sure at least some of the input power wires can be combined. I would also fish around extra hard for additional plugs; maybe they're just buried deeper under the carpet?
    Last edited by moroza; 01-10-2020 at 08:32 PM.

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    Thanks so much Moroza! I can't check the harness in the Alpina right now as we are in a deep freeze and the car is a popsicle outside. My plan is to utilize the factory harness and install proper connector pins in the right places with constant hot, accessory and ground in the right places. If I recall correctly, the harness in the car did have both a constant hot and an accessory hot so it's a matter of moving those pins to the correct places and possibly splicing into them where I need more than one lead.

    On the controller, there is that one location that is missing a plug - the 4 pin one in the picture. Is there uspposed to be a harness under the carpet to plug into that too?

    At the end of the day, all I care about is having full seat functionality (all movements and heat). I don't overly care about memory - nice to have but not imperative.

    The kids:
    Alpinas: 91 E34 B10 Biturbo; 91 E32 B12 5.0; 91 E34 B10 3.0 Allrad (mom's car); '91 B10 3.5
    Bimmers: 91 E31 850; 93 E34 525i w/ aftermarket turbo; '01 X5 4.4; 93 E31 850i Dinan TT; 89 E32 750il Dinan TT; 92 750il w/ S70 engine and transmission
    Mercedes: 92 600sel; 93 S600 Lorinser
    VW: 04 Jetta GLS TDI

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    That 4-pin plug (E) contains primary power and both grounds, so yes, it's supposed to be used. Part of what I need to verify is whether the X603 plug is present or used on memory seats. Perhaps it's there just for heat? X603 is a 12-pin, physically incompatible with the five listed. That means you'll need either an adapter harness or to modify the plugs; relocating pins isn't enough.

    Looking at it again, the 1995 ETM page 0670.3-17 pretty much states outright that memory-equipped cars have a different plug at the end of F42's circuit than non-memory. So yeah, adapter harness or cut off and change the plug.

    Adapter harness should be pretty straightforward. X603 constant power (needs to be a fat 2.5mm wire) to E/2, X603 switched power to both B/2 and B/3 (or one of each if X603 has two), X603 fat ground to E/1. X603 skinny ground, if present, to E/4; if absent, combine with E/1.

    The passenger seat appears to use X604 regardless of memory (see page 0670.3-18). Should be plug-n-play.

    Heat is a different pair of plugs, but F16 powers that circuit either way via X275 and X279 (which also power the lumbar support).
    Last edited by moroza; 01-12-2020 at 07:16 PM.

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    Thanks again Moroza. I'm not going to lie, this is still a little greek to me but I am slowly catching on. lol

    In terms of an adapter harness, I do have a 1995 525i Canadian spec parts car that had power heated comfort seats in it. Do you think the harness in the chassis could be used as an adapter harness for what I'm trying to achieve?

    The kids:
    Alpinas: 91 E34 B10 Biturbo; 91 E32 B12 5.0; 91 E34 B10 3.0 Allrad (mom's car); '91 B10 3.5
    Bimmers: 91 E31 850; 93 E34 525i w/ aftermarket turbo; '01 X5 4.4; 93 E31 850i Dinan TT; 89 E32 750il Dinan TT; 92 750il w/ S70 engine and transmission
    Mercedes: 92 600sel; 93 S600 Lorinser
    VW: 04 Jetta GLS TDI

  6. #6
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    There's an auxiliary harness for cars with memory that connects to the main seat plug then forks off to all of the square plugs on the module and in to the door harness for the mirrors. You can just plug it in to the seat if you don't need the rest to function.

    I have a photo somewhere showing how you can wire it in if you just want it to function, I'll find it and post it up.

  7. #7
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    Photo attached, hope it helps

    image001.jpg

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    Thanks for posting that diagram. Ultimately I need to get this car in the garage and see what I have in the existing harness. My biggest thing right now was I wanted to bench test the seat to check for functionality and correct any issues, like seat twist. I just don’t know what pins need power and ground on the seat to test the overall seat

    The kids:
    Alpinas: 91 E34 B10 Biturbo; 91 E32 B12 5.0; 91 E34 B10 3.0 Allrad (mom's car); '91 B10 3.5
    Bimmers: 91 E31 850; 93 E34 525i w/ aftermarket turbo; '01 X5 4.4; 93 E31 850i Dinan TT; 89 E32 750il Dinan TT; 92 750il w/ S70 engine and transmission
    Mercedes: 92 600sel; 93 S600 Lorinser
    VW: 04 Jetta GLS TDI

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    Quote Originally Posted by cdnalpina View Post
    Thanks again Moroza. I'm not going to lie, this is still a little greek to me but I am slowly catching on. lol
    I would hesistate to do much beyond plugging stuff in without a basic understanding of how electrical circuits work. Consequences of error are probably limited to blown fuses, but fires and serious electrical damage are possible as well. Be honest, what's your skill level here? Do you know how to use a basic multimeter and soldering iron?

    In terms of an adapter harness, I do have a 1995 525i Canadian spec parts car that had power heated comfort seats in it. Do you think the harness in the chassis could be used as an adapter harness for what I'm trying to achieve?
    Not if it didn't come with memory seats.

    Quote Originally Posted by t.wak View Post
    Photo attached, hope it helps

    image001.jpg
    Incomplete photo and it looks homemade, but that black plug looks like it fits the X603 plug on the body side.

    Quote Originally Posted by cdnalpina View Post
    Thanks for posting that diagram. Ultimately I need to get this car in the garage and see what I have in the existing harness.
    Agreed.

    My biggest thing right now was I wanted to bench test the seat to check for functionality and correct any issues, like seat twist. I just don’t know what pins need power and ground on the seat to test the overall seat
    To test seat motors, +12V to E/2, ground to E/1... in theory. Actually, the plugs in your photo don't quite square with the ETM, so before anything gets accidentally fried, either someone else chimes in with new info, or wait til I get home and investigate my memory seats.

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    Sorry I was maybe being a bit dramatic with that comment. I do find following through the ETM a bit confusing at times but I can fumble through it. Honestly was just looking for an easy answer lol. As for my skill level I would say intermediate. I have chased shorts in vehicles, wired up various things and wired my entire basement when I developed it. I would say I am adept at soldering and using a multimeter but certainly not an expert at reading electrical diagrams. I totally hear you on wanting to avoid fires etc.

    From what you are saying the seat memory may not be an option - and I’m fine with that. I just would like all the power options to ideally function (thigh support a nice to have) and I especially want the heat to work.

    The kids:
    Alpinas: 91 E34 B10 Biturbo; 91 E32 B12 5.0; 91 E34 B10 3.0 Allrad (mom's car); '91 B10 3.5
    Bimmers: 91 E31 850; 93 E34 525i w/ aftermarket turbo; '01 X5 4.4; 93 E31 850i Dinan TT; 89 E32 750il Dinan TT; 92 750il w/ S70 engine and transmission
    Mercedes: 92 600sel; 93 S600 Lorinser
    VW: 04 Jetta GLS TDI

  11. #11
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    Hi Rob,
    How's that fancy 7er?
    I dealt with swapping seats a long time ago and my recollection is that swapping a non-memory seat harness onto the memory seat(ignoring the pots on each motor) is the way to go unless you have the intermediate harness (61 12 8 366 855*). I think you can plug the memory seat in but will have limited functions.
    easiest way to check functions on the bench is to simply power the motors. The one that operates the recline mechanism is right in front.
    * supposedly NLA, check your PM
    Oh, the intermediate harness install is yeoman's work.
    Last edited by ross1; 01-13-2020 at 12:31 PM.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

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    Quote Originally Posted by cdnalpina View Post
    Sorry I was maybe being a bit dramatic with that comment. I do find following through the ETM a bit confusing at times but I can fumble through it. Honestly was just looking for an easy answer lol. As for my skill level I would say intermediate. I have chased shorts in vehicles, wired up various things and wired my entire basement when I developed it. I would say I am adept at soldering and using a multimeter but certainly not an expert at reading electrical diagrams. I totally hear you on wanting to avoid fires etc.
    Good, sounds like this is well within your abilities.

    From what you are saying the seat memory may not be an option - and I’m fine with that. I just would like all the power options to ideally function (thigh support a nice to have) and I especially want the heat to work.
    Actually, I would expect the memory to work, minus the mirrors. As for heat, my recollection is different from what I see in the ETM; it says the later heated seats, with fancy black-box transistorized switches, are powered by a 0.5 (skinny) gauge wire. That doesn't sound right to me per se, and furthermore I recall there being a fat switched hot wire (in addition to a fat constant hot) on a 1994 car, in which I have early (crude series/parallel with no transistors or other components) heated seats installed. I'll get home in about a week and verify what's going on with that and the memory harness.

  13. #13
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    Hey Ross,

    The 7 is so fun. Had some custom performance chips done for it so it pushes over 400hp now and well over 400 ft lbs - super fun car to drive, especially with the E32 750il rear drive ratio.

    Thanks for the link to that harness - not cheap but an option for sure. I'd rather build my own if I can as I can pilfer the chassis side of the harness from my '95 525i parts car. If that mission faisl, at least there is this option. Yes, powering the motors directly is certainly a way I can go about this. I was hoping to power them through the seat module to also ensure the module is good - beggars can't be choosers though!


    Moroza

    Thank you - I appreciate your help with this. This is a winter project so no huge rush. I just want to transplant the seats from my Alpina into an E23 745i I am working on, and in doing so finally put these nice buffalo seats to good use instead of decorating my storage shelf.

    Cheers!

    The kids:
    Alpinas: 91 E34 B10 Biturbo; 91 E32 B12 5.0; 91 E34 B10 3.0 Allrad (mom's car); '91 B10 3.5
    Bimmers: 91 E31 850; 93 E34 525i w/ aftermarket turbo; '01 X5 4.4; 93 E31 850i Dinan TT; 89 E32 750il Dinan TT; 92 750il w/ S70 engine and transmission
    Mercedes: 92 600sel; 93 S600 Lorinser
    VW: 04 Jetta GLS TDI

  14. #14
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    The memory harness you need can simply be unplugged from a parts car with memory seats. If your 95 525 doesn't have memory seats, it won't have the correct harness, it will have the same large white connectors as your car would currently have tucked away under the carpet.

    If you don't need the memory function for the mirrors, you can chop up the loom a bit to make it easier to remove then butt off those unused wires correctly.

    @Moroza - yes it is chopped up and home made, this was the guide I used to bench test my seats before installing them with the full harness. Worked a treat, but my car may be different to others due to the build dates of course. Mine is a 92 and I fit memory sports seats originally from an early E32. From memory I got that photo from someone who installed E34 sports seats in an E28.
    Last edited by t.wak; 01-14-2020 at 04:54 AM.

  15. #15
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    First of all I hope everyone and their loved ones are safe, healthy and well during this covid madness.

    I finally got a chance to see what the connector had for wires in the Alpina. It’s extremely underwhelming. When I put the volt meter on the wires, using the brown with stripe as ground, I get nothing with key off and 1.93v with key in position 2. So I’m now at the point where I need to figure out how to power the seat for basic functions. Movement and heat are the biggest, I don’t care about memory. Surely there are pins I can wire power and ground to to make the seat controller come to life so I can make it work?

    Also I need to move the seats on the rails to be able to install it in the car as they are too far back and covering the mounting holes. I read about using a square drive to turn the seat motor but I can’t for the life of me see that.

    Any guidance on all of the above us appreciated! Here’s a pic of the extremely basic wire harness in the car. If it matters, the car has power mirrors.

    Cheers, Rob
    ABEC3589-762D-4490-83AE-33F3465DA44E.jpg

    The kids:
    Alpinas: 91 E34 B10 Biturbo; 91 E32 B12 5.0; 91 E34 B10 3.0 Allrad (mom's car); '91 B10 3.5
    Bimmers: 91 E31 850; 93 E34 525i w/ aftermarket turbo; '01 X5 4.4; 93 E31 850i Dinan TT; 89 E32 750il Dinan TT; 92 750il w/ S70 engine and transmission
    Mercedes: 92 600sel; 93 S600 Lorinser
    VW: 04 Jetta GLS TDI

  16. #16
    moroza's Avatar
    moroza is offline MORΩN ΛABIA BMW CCA Member
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    Anything between 0.01 and 12.0 volts means bad wiring, at least in this instance. Unfortunately, both options - running new wire or finding the break in the exising - involve the same tedious, uncomfortable work. Not sure about the passenger seat, but the driver's wiring harness comes inboard from a big loom running down the rocker. Carpet needs to be lifted, not removed. EDIT: can't quite tell from a photo, but those wires look too skinny to support either power or heat.

    To power the seats, simply feed 12V to either the main plug or each individual motor.

    I've got a million things on my plate, including a stolen vehicle case that has ballooned into multiple felonies, but I'ven't forgotten about your memory seat quest. Will try to find some time to poke at them and see what's what.

  17. #17
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    Thanks for the reply Moroza, sorry to hear about the stress you’re going through with the stolen vehicle - hopefully that doesn’t continue to balloon further.

    The wires are indeed super thin in that harness, nowhere near the thickness of the main power and ground wires I’ve seen on other body harnesses.

    Supplying 12v to the main plug on the seat seems the way to go to me, I’m just not sure which pins require 12v on the seat harness. Can it be as simple as all pins that are brown (or brown with stripes etc.) are ground and the rest require power? Or would some of those wires simply be signal wires using a lesser voltage? The optimist in me hopes it can be done that simply lol. The good thing with the connector on the body being so void of wires is I can get proper connector pin inserts and reuse the connector to properly plug into the seat.

    cheers

    The kids:
    Alpinas: 91 E34 B10 Biturbo; 91 E32 B12 5.0; 91 E34 B10 3.0 Allrad (mom's car); '91 B10 3.5
    Bimmers: 91 E31 850; 93 E34 525i w/ aftermarket turbo; '01 X5 4.4; 93 E31 850i Dinan TT; 89 E32 750il Dinan TT; 92 750il w/ S70 engine and transmission
    Mercedes: 92 600sel; 93 S600 Lorinser
    VW: 04 Jetta GLS TDI

  18. #18
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    The pic of the "home made" connector (Looks like BigAnts pic) is what I used to install e32 seats with heat into my e23. I didn't care about the memory functions so I ignored those. So you would just have to run heavier gauge wires for 12V, ground and switched 12V. Light switch power if you want to.

  19. #19
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    Quote Originally Posted by cdnalpina View Post
    Supplying 12v to the main plug on the seat seems the way to go to me, I’m just not sure which pins require 12v on the seat harness.
    On X18323, 4-pin...
    Give +12V to pin 2, a fat red/yellow
    Ground pins 1 (fat brown) and 4 (skinny brown/orange)

    Can it be as simple as all pins that are brown (or brown with stripes etc.) are ground and the rest require power?
    No.
    Or would some of those wires simply be signal wires using a lesser voltage?
    A lot of those are signal wires, yes. Probably not with lesser voltage, but strange things may happen if they get a signal when they aren't expecting it.

  20. #20
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    That picture with the white connector and only 2 wires (blue/purple/yellow) (brown/orange) is probably for your seatbelt switch, as you mentioned the car had only manual seats.
    One option could be to find a "normal" seat harness without memory to replace the existing one inside the seats, then you only need to wire + and ground to get the seats moving.

  21. #21
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    Do you have the intermediate harness from the donor car hooked up to the drivers seat?

    int_harness.jpg

  22. #22
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    Unfortunately I don’t have the donor car - long gone years ago. I do have a 95 Canadian spec 525i parts car though and it had heated comfort seats. Would harnesses from that car work?

    The kids:
    Alpinas: 91 E34 B10 Biturbo; 91 E32 B12 5.0; 91 E34 B10 3.0 Allrad (mom's car); '91 B10 3.5
    Bimmers: 91 E31 850; 93 E34 525i w/ aftermarket turbo; '01 X5 4.4; 93 E31 850i Dinan TT; 89 E32 750il Dinan TT; 92 750il w/ S70 engine and transmission
    Mercedes: 92 600sel; 93 S600 Lorinser
    VW: 04 Jetta GLS TDI

  23. #23
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    OK - time for a big UPDATE!

    With the help from people here and a good friend of mine Omegaman, who is an electronics wizard, I have mostly solved the mystery of making my seat swap work! I will summarize everything below, and please chime in for any additional comments.

    Background:
    - I have a set of heated buffalo sport seats with memory, the usual electric seat motions, lumbar and thigh support from a canadian spec 1995 540i
    - I wanted to put them into a 1995 Alpina B10 3.0 Allrad (525ix) that came with unheated, no memory (obviously) manual seats from the factory
    - I have a 1995 Canadian 525i spec parts car that has heated, power comfort seats - no memory

    There had been some great suggestions here about pulling an 'intermediate' harness' from a donor car and I attempted to do this with my 525i parts car. For the life of me I could not figure out what the intermediate harness was. I pulled up the carpet and pulled the wiring looms from the driver's and passenger sides, but there wasn't simple 'connector to connector' type of harnesses I could pull from this particular car with ease. Wires that fed into the driver's harness had a few wires that came from the main large connector at the firewall, then the balance of the wires as well went to the terminations under the rear seat for ground and power and to the passenger harness. Maybe the Canadian spec car I have did not come with this intermediate harnesses? No matter, just posting my particular observations.

    That said, I yarded out as much of the harnesses as I could to use as donor harnesses to wire up my 540i sport seats. However... the connectors did not match up to the seat connectors - the orientation of the grooves matched but the shape of the connector on the narrow ends varied. So unfortunately I could not plug them in to trouble shoot my wiring issue. Luckily I had a set of harnesses from another parts car that fit.

    Seat differences:
    Interestingly the 540i sport seats have a seat module under the driver's side - the 525i did not. Both had the 12 pin wiring harnesses, however wire orientation and some colours between the seats varied. Passenger seats were basically the same with only 12 pin wiring harnesses but variation in some wire colours between the two.

    Wire tracing:
    Before I cut the harnesses out of my 525i parts car I checked the body harness to see which pins are HOT and which are ACC. I documented this and if it is of value for any of you I can post a screenshot of the spreadsheet I made up for that. Being that the seats only use the 12 pin harnesses for these seats it is fortunately pretty straight forward.

    Now powering the sport seats - this was a shift but I have most of it sorted out. Looking at the seat module under the driver's seat, there are 4 male pins. The pins are labelled 1-4: pins 1 and 4 need ground; and pin 2 requires power. When this is done, you gain power to the main adjustment switches on the side of the seat (front, back, tilt, seat back and lumbar). What's missing is the seat heat, thigh support and possibly memory (not sure on this yet as I have yet to test it).

    In BMW wiring language, I have learned that green with black stripe is seat heat power feed. Also, the Grey with a black stripe is power for illumination for the switches. So, on the 12 pin harness, when i supplied it with ground to the big brown wire, and power to the green black stripe and grey black stripe I gained the missing seat heat and illumination functions.

    Missing in all of this is the thigh support and possibly memory (will test once I have the seats installed in the car) I tried every combination and nothing yielded any movement. I even tried removing the switch and supplying power directly to the pins on the harness and no action. So I have have a dead motor or some other issue there. At the end of the day, I have the core functionality that I was hoping to get from these seats. However, if anyone has some guidance or suggestions on how to get the front thigh support to function I am all ears!

    I can post pictures of everything I have done if that helps - let me know.

    Thanks everyone for your help and guidance on this seat journey - I'm relieved that I have this mostly resolved now.

    Cheers,

    Rob
    Last edited by cdnalpina; 04-26-2020 at 02:59 PM.

    The kids:
    Alpinas: 91 E34 B10 Biturbo; 91 E32 B12 5.0; 91 E34 B10 3.0 Allrad (mom's car); '91 B10 3.5
    Bimmers: 91 E31 850; 93 E34 525i w/ aftermarket turbo; '01 X5 4.4; 93 E31 850i Dinan TT; 89 E32 750il Dinan TT; 92 750il w/ S70 engine and transmission
    Mercedes: 92 600sel; 93 S600 Lorinser
    VW: 04 Jetta GLS TDI

  24. #24
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    No intermediate harness without memory.
    Rob, If you need a seat motor let me know I have a couple I think are same.
    Last edited by ross1; 04-29-2020 at 07:58 AM.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  25. #25
    Join Date
    Sep 2017
    Location
    Vienna, VA
    Posts
    198
    My Cars
    1995 525i E34 6-speed
    Quick idiot check: the xdrive and non-xdrive seats are compatible correct? I know there is a bulge into the cabin from the trans tunnel for the transfer case. And I know it is big enough that the floor mats for the Xdrive cars are different. In theory that means the differences are forward of the seat, but thought I would bring it up.

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