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Thread: Door lock actuators not getting power/signal E34

  1. #1
    Join Date
    Dec 2003
    Location
    Australia
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    423
    My Cars
    95 525TDS, 94 525iT

    Door lock actuators not getting power/signal E34

    Hi all,
    Recently picked up a 9/92 build 525i touring and it's in pretty good shape apart from a few niggles - the main one being that the central locking doesn't work!
    Things I've tried (not including a lot of Googling):
    -New general module
    -New relay module
    -Checked all fuses with multi-meter (only one blown - which was for the aux fan)
    -Checked fusible link
    -Powered actuators directly through the door loom while unplugged from the body loom, actuators react when powered on the correct pins

    Interior lights and electric windows work perfectly! When you trigger the central locking using the drivers side pin, door barrel or boot lock, the RM clicks, but no locks operate. Not even the fuel cap lock

    What would cause there to be no power getting to the actuators? Should I start pulling fuse boxes out to check for any bad connections and corrosion? Everything looks very clean under the back seat without any signs of water damage or misuse. Could there be another relay I haven't identified?

    Appreciate any guidance.

  2. #2
    Join Date
    Dec 2004
    Location
    CT, USA
    Posts
    4,161
    My Cars
    e28, e34, e39
    Check the two trigger wires behind the left front speaker. You should see a brief 12 volts signal on the lock or unlock wire when you lock or unlock. Depending on your results, you can move forward or backwards from there.
    demet

  3. #3
    Join Date
    Mar 2007
    Location
    Indiana
    Posts
    527
    My Cars
    '91 318is, '93 525iT
    None actuate at all? That is odd.

    One possible source of issues would be the splices under the rear seat and carpet, especially if your car had a leaky heater core that leaked into the interior at some point. On my Touring, the driver front door wasn't getting power to any of the central locking bits, and the culprit was the X481 splice under the rear carpet on the driver's side of the trans tunnel. Could conceivably cause failure for all central locking power feeds depending on how it failed. Pictures can be found in my build thread here: https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1993-525i-touring-impulse-build/123652/page3/

  4. #4
    Join Date
    Jun 2009
    Location
    Macon, GA
    Posts
    1,224
    My Cars
    '94 530iT/A|'95 540iT/6
    Quote Originally Posted by gearheadE30 View Post
    None actuate at all? That is odd.

    One possible source of issues would be the splices under the rear seat and carpet, especially if your car had a leaky heater core that leaked into the interior at some point. On my Touring, the driver front door wasn't getting power to any of the central locking bits, and the culprit was the X481 splice under the rear carpet on the driver's side of the trans tunnel. Could conceivably cause failure for all central locking power feeds depending on how it failed. Pictures can be found in my build thread here: https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1993-525i-touring-impulse-build/123652/page3/
    +1

    Scroll down in this post for a few pictures of what you are looking for:
    https://www.bimmerforums.com/forum/s...2#post29161852

  5. #5
    Join Date
    Dec 2003
    Location
    Australia
    Posts
    423
    My Cars
    95 525TDS, 94 525iT
    Thanks guys, time to start tracing wires it seems!

    It is strange that none of the actuators in the entire system work, but the relay module still clicks along. I'll keep this thread updated with any progress.

  6. #6
    Join Date
    Apr 2004
    Location
    Anacortes,WA
    Posts
    1,300
    My Cars
    E34 535i; E36 325is
    Can the door lock actuators be simply disconnected at the mechanical link, and the door locks operated by old-fashioned turning of the key in each lock or pushing/pulling each knob?

  7. #7
    Join Date
    Dec 2003
    Location
    Australia
    Posts
    423
    My Cars
    95 525TDS, 94 525iT
    They all lock and unlock perfectly fine manually. This has been put on the back-burner until I have a spare weekend to throw at it, so no progress yet.

  8. #8
    Join Date
    Apr 2004
    Location
    Anacortes,WA
    Posts
    1,300
    My Cars
    E34 535i; E36 325is
    Wiring gremlins re. door locks, etc.:

    I removed the black plastic sheath over the wire loom which attaches to the left side trunk lid hinge, and found that of 15 wires, 8 had worn through the insulation, and two were completely broken. The broken wires were the blue/yellow and the brown (ground?) wire. Reattached/reconnected these broken wires in hopes the central door lock systems would work, but found no change whatever... So, there's another fault(s) somewhere else.

    From this, I recommend starting your diagnosis and repairs with the trunk hinge loom.

  9. #9
    Join Date
    Dec 2003
    Location
    Australia
    Posts
    423
    My Cars
    95 525TDS, 94 525iT
    Checked the tailgate wiring and only found one broken wire which was repaired... Which let me open the tailgate glass - but unfortunately no change in the central locking.

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