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Wiring in Recaro seats, need guidance from experts

Discussion in 'General Electronics Discussion' started by MichaelsVintage, Apr 8, 2017.

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  1. MichaelsVintage

    MichaelsVintage

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    Apr 8, 2017
    Hello everyone!

    Please don't be scared by all the text!

    My name is Mike Clifford, and I work on vintage race cars for a living. I take care of European sports, formula, and sports racing cars from the 1950s and '60s, and take them to tracks all over the Eastern U.S. It's different and quite a bit of fun, but I'm sharing that to show why I have so little electrical know-how : )

    My daily driver is a 1987 BMW 325i. I just bought an awesome pair of Recaro seats for it. Both seats have heat power reclining, and a little air compressor which fills lumbar bladders.

    I'll be wiring the heating elements in using the factory wiring harness and plugs, so no issues there. I need help with the wiring for the recline and the compressors, however.

    Each seat has a red wire and a brown wire which control both functions. The buttons to control recline/air compressor are on the seat, and they're lighted. This was my plan for wiring these into the car:

    The car has an auxiliary fuse box from the factory with a hot lead and a switched lead. Since the buttons have lights, I need to attach them to switched power to keep from draining the battery. My thought was to wire in a 4-pin relay. The power source pin would run to the fused hot lead, the switch pin would run to the switched lead, the load pin would run to the red wire on the seats, and the ground pin would run to the brown wire on the seats.

    Since there are two seats, it was my thought to tap into the load wire and ground wire running to the first seat and tee off to the second seat. The relay and fuse are rated for enough current to handle simultaneous load from both seats.

    Please let me know what's correct and what should be done differently. I can provide photos of the seat, seat wiring, auxiliary fuse box, and whatever else may help.

    I want to make sure this is done correctly and this seems like a great place to find some help!

    Thank you in advance!
     
  2. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    651
    May 8, 2012
    This is my personal opinion but I think our premier photo decipher guy is ED. He's a retired (I think) NASA engineer. Let's see if I can drag him over here. If he responds you can't miss him. His avatar is a photo of him in his white NASA smock. His avatar says "NASA", so you can't miss him.

    I thought I could help but I'm a schematics guy. Besides that, I haven't been feeling myself lately and find the only thing that seems to take the edge off is a quart of Pinot, or equivalent mind numbing beverage.

    Chris
     
  3. MichaelsVintage

    MichaelsVintage

    9
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    Apr 8, 2017
    Here are some pictures of the seats and the wiring I'm talking about:
    Seat:
    [​IMG]

    Control buttons (the two top ones light up):
    [​IMG]

    Red and brown wire from seat (the blue wires are for heat, ignore those):
    [​IMG]

    Auxiliary fuse box on the car:
    [​IMG]

    and here's a shot of the car for reference :)
    [​IMG]
     
  4. MichaelsVintage

    MichaelsVintage

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    Apr 8, 2017
    Thanks, Chris! Hopefully you start to feel better. I've found racing cures just about any ailment ;)
     
  5. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    651
    May 8, 2012
    Hello Michael, I sent Ed an alert. With any luck he's as photo sharp as he always is.

    BTW, I always welcome nubes to EP but I now see I was remiss. Soooo.....

    Welcome To Electronics Point!

    Chris
     
  6. 73's de Edd

    73's de Edd

    3,070
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    Aug 21, 2015
    Sir Michael. . . . . . . .

    BY JOVE . . . . methinks . . . . . that it’s a bloomin’ bloody BEEEEEMER !

    Looks like your RECARO hopes and aspirations were rapidly dashed and shut down by the great Sunroof / Heater / Lockout / Interlock Debacle . . . . . . . . . .syndrome.

    Looking at the pulled seat resting upon the driveway and its 6 wires lying out there . . . . no . . .TIME OUT . . . one small twisted pair is now actually seen as being a crack in the driveway.

    Soooooooo . . . with your forthcoming info of disregarding the GREEN as being peter heater related circuitry (which I have marked in pale GREEN to simplify the schematic wiring by being non relevant.) we now have this.

    The seat switching related relays . . . . pale YELLOW . . . the drive motors . . . pale GRAPE . . . and the seat adjustment pushbutton circuitry . . . pale BLUE . . . have also been marked up.

    That leaves you with just having a POWER (RED) and a GROUND (BLACK) / BROWN)
    connection for the seat mechanism.

    Scan over the provided referencing and you will see that you neglected to additionally acquire the PINK box referenced circuitry.

    To get your mentioned switching actions you need to build up the simple ancillary circuitry now depicted within the BLUE box referencing.

    Probably easiest and cheapest is to go to an auto junque yard and seek out the big ‘ole Jig-wars, Mercy-days and Rollin’ Roysters, to find one of their heavy duty Bosch or AEG or Wolfhangenbangenschmidt relays.

    It, being of the “85-86-87-30” series of a 4 connection SPST automotive power relay, along with ita mating plug in socket,, a plug in fuse holder and its/a 25A link fuse.

    Then build up according to the BLUE box circuit, with connection into the RED power circuit and BLACK ground return, with the new relay getting its “86” needed ground with a sharing of the BLACK connection.

    Thassssit . . . . .

    TECHNO-REFERENCING :

    [​IMG]

    http://i.imgur.com/tdn2pMM.png


    73’s De Edd
     
    Last edited by a moderator: Apr 9, 2017
    CDRIVE and davenn like this.
  7. 73's de Edd

    73's de Edd

    3,070
    1,299
    Aug 21, 2015
    Soooooooo . . . with your forthcoming info of disregarding the GREEN . . . .corrects to . . .
    Soooooooo . . . with your forthcoming info of disregarding the BLUE
     
  8. MichaelsVintage

    MichaelsVintage

    9
    0
    Apr 8, 2017
    Edd,

    Thank you for your prompt and colorfully-worded reply! I hadn't noticed that crack in the shop floor, haha...

    By the way, I'm extremely impressed by your career choice; I've always loved aeronautics and aerospace, and NASA's budget (or lack thereof) has frustrated me most of my life.

    Anywho, back to the wiring. I've purchased a new Hella 4-pin relay because I've chased my tail before using a junkyard relay (clicked fine, but the internal resistance was no longer correct/in spec).

    This is how I'm interpreting the very helpful diagram with respect to my wiring situation:

    Pin 30 (power in) = the red, fused, constant-hot in the auxiliary fuse box
    Pin 85 (activation pin) = the green ignition-switched in the auxiliary fuse box
    Pin 87 (switched power out) = runs to the red wire on each seat
    Pin 86 (ground) = runs to the brown wire on each seat

    I see you mentioned combining the brown wires/ground is no issue; is there any potential problem attaching the red wire from both seats to the single pin 87 on the relay? Both the fuse and the relay are rated for more amperage than the combined draw from both seats.

    I can't tell you how much I appreciate the help, this has been a stressful process trying to make sure this gets done the correct way.

    -Mike
     
  9. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    651
    May 8, 2012
    Ed, you never cease to amaze me!

    Micheal, I'm going to leave you in good hands?

    Cheers,
    Chris
     
  10. MichaelsVintage

    MichaelsVintage

    9
    0
    Apr 8, 2017
    Thanks Chris, feel better!
     
  11. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    651
    May 8, 2012
    Thank you I'm in the process of executing that at this very moment.

    Good luck,
    Chris
     
  12. MichaelsVintage

    MichaelsVintage

    9
    0
    Apr 8, 2017
    So today is the day I'm doing the wiring.

    I thought the heated seats were going to be a slam dunk, but of course that's not the case.

    As previously mentioned, the seat just has two wires coming from it for the heated seats. The elements are wired in series.

    The plug from the harness to each seat of course has four wires.

    The heated seat switches have a "high" and "low" setting.

    Here's the factory schematic:
    [​IMG]

    Is there any way for me to make the two-wire seat work with the high and low parts of the switches? If not, how can I wire the heaters to just work?

    Thanks in advance.
     
  13. 73's de Edd

    73's de Edd

    3,070
    1,299
    Aug 21, 2015
    Okay if your unit has a high and low heat switch position which neither one of our diagrams referred to as such, it must be wired in between the four pin connector from the heater elements up to the wiring above.
    The presently shown wiring diagram is having the back and seat heating elements wired in series .
    To get a high and low heating option would have the high / low switch alternating between series arrangement of the heating elements for low heat to parallel arrangement of the heating elements for high heat .
    You have a BLUE and a BLUE /WHITE trace wiring for your two heater connections, if going by the present wiring protocol, the BLUE / WHITE trace unit would be the 12VDC hot wire. while the BLUE would be for ground .
    To confirm this, take a naked chair and concentrate on the blue white and blue wire and connect them to an ohmmeter leads to get a resistance reading .
    With the seat heater switch on , and the low / high heat position in the low position you should get a resistance reading .
    Flipping the switch to high should then reflect a resistance reading about one half of the previous reading .
    Try it out now.

    73's de Edd

    .
     
  14. MichaelsVintage

    MichaelsVintage

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    Apr 8, 2017
    My issue is thus:

    The seat has the two wires pictured above. If I'm understanding correctly, those can be wired in either "direction," e.g. polarity doesn't matter because it's just a giant resistor basically.

    The wiring harness has both the switches (high/low) and the connector which would have plugged into a stock-type seat. This connector has 4 wires. You are correct that the "low" setting on the switches just cuts the voltage to each pad in half from the full 12V to 6V.

    Since my seat only has two wires (instead of the four which come out of a stock seat), I cannot currently plug it into the harness. Is there any way to use the 4 wires coming from the harness to achieve the high and low settings? In other words, can a 4-in, 2-out setup allow a cut to 6V at the seat, or does one need the four separate wires coming from the seat to achieve this?

    Here's a photo of the seat plug on the harness:

    [​IMG]
     
  15. MichaelsVintage

    MichaelsVintage

    9
    0
    Apr 8, 2017
    By the way, I just tested the relay setup for non-heat functions at both seats and it appears to be working! :D
     
  16. 73's de Edd

    73's de Edd

    3,070
    1,299
    Aug 21, 2015
    Sir Michael. . . . . . . .


    Beemer wiring diagrams covering your vintage and particularly heated seats aspects are rare birds.
    Even your submission and mine are differing on the wiring color codes.

    [​IMG]

    http://i.imgur.com/9GhRL66.png



    Black Red trace and Black Green I suspect to be minor players, while YELLOW and BROWN, I might suspicion to be the HOT 12VDC and GROUND wires.

    And I have forgotten the “BUZZ” word that they used and assigned to the relay that disconnects your heated seat circuitry when the ignition switch is off . . .Possibly ? K5 or K7 " UNLOADER " relays.

    So, why not confirm that BROWN is ground and that Yellow is your hot switched 12VDC.

    If not being 12VDC switched you would need the right diagram built up.

    Then you cut the connectors from the Beemer seats to use to mate together and wire into the BLUE /WHITE hot and BLUE Ground of the RECARO, really, of no polarity importance , since no LED indicators or other electronics, whereas I believe that the Beemer did use transistors in it.

    If re selling the Beemer seats .a la . .no connectors . . . . OHHHHHH you are supposed to use the connector off from your old inoperative seat that you are replacing !


    When you successfully complete this . . . . be sure to finally ask me about item 9 and the backs of the RECARO seats.


    Thasssssit . . .


    73’s de Edd
     
    Last edited: Apr 19, 2017
  17. MichaelsVintage

    MichaelsVintage

    9
    0
    Apr 8, 2017
    Another great diagram, thank you! So I'll utilize only the "high" side of the switches; works for me! I plan to check this wiring in the near future, although I need a short break after the initial wiring and seat installation :)

    Speaking of, here are some photos of the seats installed in the car! The lighted buttons, power tilt, and air compressors are working perfectly using the wiring and relay we came up with.

    [​IMG]

    [​IMG]

    [​IMG]
     
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