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Thread: Driver seat shoulder support not working

  1. #1
    Join Date
    Jul 2013
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    Norcal
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    1998 740il dinan 7

    Driver seat shoulder support not working

    Hey guys, I actually had the passenger shoulder support not working at one point and turned out to be a loose connection. wiggle and problem solved. This time, my dad's 740 has it happen on his driver side. I do hear the motor clicking but no movement back or forth. I did some searches but nothing came up except another person posted the same problem on bimmerboard with no answers either. Just wondering if there's a fix for this. Thanks!

    Oh, My mother took the car to smog and she is 4'11". The smog guy she claimed was a huge man and after he smogged the car, the seat stopped responding to all commends. She tiptoed her way home with the bimmer.... not safe! but now that I am here to fix it, its working just fine! wtf, anyone else run into this intermittent problem?

  2. #2
    Join Date
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    15 650ix GC & 14 X5 50i
    If the plastic seat cover around the base of the seat is loose...did you check the wiring harness to the seat? When the cover is loose, it can cause the wiring harness to break at the control module...as drivers get in/out of the seat...the harness can slip in/out causing seat & steering wheel malfunctions.

    Broken neck on seat control module allows wiring harness to slip out



    Last edited by Qsilver7; 11-08-2015 at 02:00 PM.
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  3. #3
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    1998 740il dinan 7
    I will look at that asap. as for the shoulder support, any ideas? I can actually hear the motor and some vibrations at the shoulder support portion of the seat but no actual movement of the shoulder support.

  4. #4
    Join Date
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    Check the harness first for both issues (upper seat back and total seat movement). The harness also has a (white) locking mechanism which is missing in the pic above where you can see the harness & seat control module with broken neck. If this is what has happened...the harness can slip out at an angle and sometimes pins can get bent causing either total malfunction or spotty malfunction.

    Also, if the cable for the upper articulating back on the passenger side was loose...perhaps the cable on the driver's side has slipped out of or disengaged from its motor. The flex cables & actuators in the front seats have been known to do this on BMWs for decades...it goes back to the e28/e32/e34/e36 models of the late 70s/80s/90s.

    Check #11 & #12 & #13 (see diagram below) for proper operation of the seat back, upper articulating back, and flex shaft:

    Last edited by Qsilver7; 11-09-2015 at 08:55 AM.
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  5. #5
    Join Date
    May 2015
    Location
    Scotland
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    11
    My Cars
    E38(750i,740i) E39 528i
    My early E38.. a 94’ 740i has EXACTLY the same fault with the drivers countour comfort seat in which the top half/headrest/shoulder tilt is stuck in its furthest back position. All other seat fucntions work just not the optional extra top half tilted seatback (The horizontal forwards & backwards arrow switch on the top of the seat base.

    When pressing the button nothing happens, no noise from the motor at all. I pulled the switch out of the seat and had a tug at the wires, still nothing. Anyone got any idea of what it could be? Is there a fuse that controls this contour seat switch alone? As I say all other seat functions work (Seat recline, forwards/backwards, up and down, lumbar etc).

    It’s a bit annoying being stuck in pacs position.. even with my seatback all the way forward and headrest raised high my neck still snaps back under hard acceleration.. man that M60 4.0 V8 can still go like its 1994.

    I was thinking about swapping the passenger comfort seat switch over to the drivers side, could someone talk me through this? (Cutting wires etc not my strongest point) The fact the motor is making no noise leads me believe it could be a fuse. This is the most annoying fault as it makes this car so uncomfortable to drive. The passenger side shoulder tilt is working after fiddling with the wires. I have been trying to sort this for years! Absolutely no noise from the drivers side shoulder tilt motor, is it a fuse and where is the fuse?

    I have posted this on various other bmw forums over the years without any luck, hopefully reserecting this old thread will help!

  6. #6
    Join Date
    Jan 2019
    Location
    thailand
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    My Cars
    BMW 5 e28
    That will really hurt ones back if not properly installed.

  7. #7
    Join Date
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    99 840ci Sport Indv
    The relevant fuse is Fuse 15....
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  8. #8
    Join Date
    May 2015
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    E38(750i,740i) E39 528i
    Thank you! Is this fuse in the glovebox or the trunk?

  9. #9
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    Quote Originally Posted by Timm View Post
    The relevant fuse is Fuse 15....
    Quote Originally Posted by GmanV12x View Post
    Thank you! Is this fuse in the glovebox or the trunk?
    The glovebox fuses run from F1 - F48...the trunk fuses run from F49 - F77 (the trunk fuse index is on the back of the battery compartment pull down door)
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