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Thread: Got A Weird One - At Least I Think So! Lights & Trunk...

  1. #1
    Join Date
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    Got A Weird One - At Least I Think So! Lights & Trunk...

    Gentlemen (and Ladies?)

    1991 850i. Recent purchase.

    Windows do not work, consequently window drop does not as well and the trunk won't open with the release, works fine with the key trick (mechanically).

    All fuses verified with correct ratings and nothing is blown. Tested across blades with DVM.
    Replaced K70 relay, trunk still not electrically operational.
    Replaced K72 relay because blades looked like the relay had been hot at one or more point(s), trunk light blinks on a 1-2 second cycle when the new relay is plugged in and a door is opened. Could have been the 1.5 amp draw referenced next???

    Was told it had a 1.5A draw. After pulling K72, draw was down to 40mA (too low?)

    With some reading, am I looking at GM re-cap or fusible link replacements, or what???

    Thank you all ahead of time. This place is amazing!

    Mike
    Mike Drives:
    BMW's
    E24 - 635CSiA - (1) 1985 (US)
    E24 - 635CSi - (1) 1985 (EC)
    E31 - 850iA - (1) 1991 (Black)
    E31 - 850iA - (1) 1991 (Calypso Red)

    E32 - 740iA - (1) 1994
    E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
    E32 - 735iL - (2) 1990
    E32 - 750iL - (1) 1990

    E38 - 740iLA - (2) (1) 1997 & (1) 1998
    E38 - 750iLA - (1) 1998
    E38 - 740iA - (1) 2000 "Short Sport"
    E39 - 528iA - (2) - 2000 & (1) 1997
    Also:
    2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
    2014 Dodge Dart Rallye (Daily Driver)
    2007 Mercedes Benz CL600 (Brabus SV12S)
    Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
    1967 Buick Riviera (2)

  2. #2
    Join Date
    Jun 2020
    Location
    Bay Area
    Posts
    314
    My Cars
    1994 E31 840ci 2000 Z3 M
    I've just replaced my fusable links today. I was struggling with a similiar issue with the window drop and the windows not working. Same with the lock mechanism. I'm about to test it, I'll let you know how it goes.

    Sent from my SM-G970U using Tapatalk

  3. #3
    Join Date
    Feb 2010
    Location
    Hampshire UK
    Posts
    8,867
    My Cars
    99 840ci Sport Indv
    The cycling of the relays usually mean a pair of dead batteries - they switch ON, the battery voltage drops - they switch OFF - the battery voltage recovers etc etc!
    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


    My BMW Repair YouTube Channel
    My Current 840ci Sport Individual
    My Current 650ci Sport Individual
    My E31 Repair and Information Website
    My E38 Repair and Information Website
    My E63/E64 Repair and Information Website

    Chase - Heroes to a generation

  4. #4
    Join Date
    Feb 2015
    Location
    Kuna, Idaho
    Posts
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    Too Many Cars (NOT!)
    Timm;
    The batteries are brand new Interstates that the PO purchased for the sale. I will test them though. I have a load tester etc. Thank you for the suggestion.
    Any chance this is also a fusible link issue? Where there is just enough of a crack that is making the link act like a bi-metal device via heat from the current?

    Goodguyili:
    Please let me know. That would be extremely interesting to discover. It's weird all the strange things fusible links can cause.

    Any other "out of the box" ideas are greatly appreciated.

    Thank you,
    Mike
    Mike Drives:
    BMW's
    E24 - 635CSiA - (1) 1985 (US)
    E24 - 635CSi - (1) 1985 (EC)
    E31 - 850iA - (1) 1991 (Black)
    E31 - 850iA - (1) 1991 (Calypso Red)

    E32 - 740iA - (1) 1994
    E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
    E32 - 735iL - (2) 1990
    E32 - 750iL - (1) 1990

    E38 - 740iLA - (2) (1) 1997 & (1) 1998
    E38 - 750iLA - (1) 1998
    E38 - 740iA - (1) 2000 "Short Sport"
    E39 - 528iA - (2) - 2000 & (1) 1997
    Also:
    2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
    2014 Dodge Dart Rallye (Daily Driver)
    2007 Mercedes Benz CL600 (Brabus SV12S)
    Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
    1967 Buick Riviera (2)

  5. #5
    Join Date
    Oct 2016
    Location
    Shoreview MN
    Posts
    977
    My Cars
    Had a 1991 BMW 850

    Links

    When you are chasing electrical problems, Fusible links are #1 on the list, Followed by #2 General Module and then start chasing battery drain by hooking up Ohmeter and start pulling fuzes to identify circuit

    Charge you batteries in case it is # 2

  6. #6
    Join Date
    Jun 2020
    Location
    Bay Area
    Posts
    314
    My Cars
    1994 E31 840ci 2000 Z3 M
    Yup. The moment i fixed my fusible links my window gremlins disappeared. It only costed me $25 in audio fuses and carriers and about an hour or 2. I've never done anything like it before but it works and was fairly simple.

    Sent from my SM-G970U using Tapatalk

  7. #7
    Join Date
    Feb 2015
    Location
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    Too Many Cars (NOT!)
    I think I'm going to go get a couple of the audio fuses. Does anyone know what amperage is supposed to be?

    The batteries live on a brand new NOCO Genius 5 through the jump post under the hood, so discharged batteries shouldn't be one of the issues. That being said, it does not preclude some weird nebulous issue with them.

    Thank you all,

    Mike
    Mike Drives:
    BMW's
    E24 - 635CSiA - (1) 1985 (US)
    E24 - 635CSi - (1) 1985 (EC)
    E31 - 850iA - (1) 1991 (Black)
    E31 - 850iA - (1) 1991 (Calypso Red)

    E32 - 740iA - (1) 1994
    E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
    E32 - 735iL - (2) 1990
    E32 - 750iL - (1) 1990

    E38 - 740iLA - (2) (1) 1997 & (1) 1998
    E38 - 750iLA - (1) 1998
    E38 - 740iA - (1) 2000 "Short Sport"
    E39 - 528iA - (2) - 2000 & (1) 1997
    Also:
    2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
    2014 Dodge Dart Rallye (Daily Driver)
    2007 Mercedes Benz CL600 (Brabus SV12S)
    Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
    1967 Buick Riviera (2)

  8. #8
    Join Date
    Jun 2020
    Location
    Bay Area
    Posts
    314
    My Cars
    1994 E31 840ci 2000 Z3 M
    If you look at the old fuses, they should say. Mine said 80 Amps so that's what I got, but I drive an 840ci so it might be different.

    Sent from my SM-G970U using Tapatalk

  9. #9
    Join Date
    Jan 2016
    Location
    Ca
    Posts
    6,981
    My Cars
    2001 525it
    Trunk issue look at the wiring going into the trunk lid from the body, broken wires. Window drop two things there is are three micro switch pack on the drivers door inside the tips on the micro switch’s get worn and don’t make good contact or the on of the switches is bad and there is this metal piece on the door latch or handle breaks or is worn I can’t remember, the piece is not available from bmw but there is this guy who makes the piece, we used it in a customers 840.

  10. #10
    Join Date
    Feb 2015
    Location
    Kuna, Idaho
    Posts
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    My Cars
    Too Many Cars (NOT!)
    Goodguyili;
    I will pull the rest of the trunk liners and check the links.

    jclausen;
    I know about the wires along the trunk hinges, on the V12's I think there is a bundle on each hinge.

    Hyper is the man when it comes to a lot of things, specially 8 series door handles. I've installed his kits in both doors of my other 850. The doors opened fine on this one and the driver's still does (the window was left down just a tad), I can't open the passenger side due to the lack of window drop. It doesn't feel like something mechanical. It feels electrical and BIG electrical besides. Going to start with battery testing, then fusible links, then mind loss...

    Thank you again,
    Mike
    Mike Drives:
    BMW's
    E24 - 635CSiA - (1) 1985 (US)
    E24 - 635CSi - (1) 1985 (EC)
    E31 - 850iA - (1) 1991 (Black)
    E31 - 850iA - (1) 1991 (Calypso Red)

    E32 - 740iA - (1) 1994
    E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
    E32 - 735iL - (2) 1990
    E32 - 750iL - (1) 1990

    E38 - 740iLA - (2) (1) 1997 & (1) 1998
    E38 - 750iLA - (1) 1998
    E38 - 740iA - (1) 2000 "Short Sport"
    E39 - 528iA - (2) - 2000 & (1) 1997
    Also:
    2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
    2014 Dodge Dart Rallye (Daily Driver)
    2007 Mercedes Benz CL600 (Brabus SV12S)
    Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
    1967 Buick Riviera (2)

  11. #11
    Join Date
    Feb 2015
    Location
    Kuna, Idaho
    Posts
    736
    My Cars
    Too Many Cars (NOT!)
    Update;

    Pulled both supposed new Interstate batteries, took them to Interstate. It appears the PO failed to replace both batteries as a pair. One was from 2019, the other 2020. The old battery killed the new battery. They no-charged the new battery and gave me a pro-rate on the old one even though it was still good.

    Replacing fusible links.

    Will update.

    Thank you all!

    Mike
    Mike Drives:
    BMW's
    E24 - 635CSiA - (1) 1985 (US)
    E24 - 635CSi - (1) 1985 (EC)
    E31 - 850iA - (1) 1991 (Black)
    E31 - 850iA - (1) 1991 (Calypso Red)

    E32 - 740iA - (1) 1994
    E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
    E32 - 735iL - (2) 1990
    E32 - 750iL - (1) 1990

    E38 - 740iLA - (2) (1) 1997 & (1) 1998
    E38 - 750iLA - (1) 1998
    E38 - 740iA - (1) 2000 "Short Sport"
    E39 - 528iA - (2) - 2000 & (1) 1997
    Also:
    2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
    2014 Dodge Dart Rallye (Daily Driver)
    2007 Mercedes Benz CL600 (Brabus SV12S)
    Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
    1967 Buick Riviera (2)

  12. #12
    Join Date
    Feb 2015
    Location
    Kuna, Idaho
    Posts
    736
    My Cars
    Too Many Cars (NOT!)
    Update;

    So, new batteries, new relays, new circuit breakers replacing fusible links. All fuses tested through their blades and correct amperage for that particular circuit.

    No change.

    Are we down to repairing the GM or is there another step I can take prior to?

    Thank you,

    Mike
    Mike Drives:
    BMW's
    E24 - 635CSiA - (1) 1985 (US)
    E24 - 635CSi - (1) 1985 (EC)
    E31 - 850iA - (1) 1991 (Black)
    E31 - 850iA - (1) 1991 (Calypso Red)

    E32 - 740iA - (1) 1994
    E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
    E32 - 735iL - (2) 1990
    E32 - 750iL - (1) 1990

    E38 - 740iLA - (2) (1) 1997 & (1) 1998
    E38 - 750iLA - (1) 1998
    E38 - 740iA - (1) 2000 "Short Sport"
    E39 - 528iA - (2) - 2000 & (1) 1997
    Also:
    2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
    2014 Dodge Dart Rallye (Daily Driver)
    2007 Mercedes Benz CL600 (Brabus SV12S)
    Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
    1967 Buick Riviera (2)

  13. #13
    Join Date
    Jun 2008
    Location
    SF Bay Area
    Posts
    3,774
    My Cars
    Supercharged 850ci
    I would say a GM module for sure!

  14. #14
    Join Date
    Feb 2015
    Location
    Kuna, Idaho
    Posts
    736
    My Cars
    Too Many Cars (NOT!)
    Thanks Dragon.

    Do you or someone happen to know Scott's handle on here. He repaired the GM from my other 850, but it was a long time ago.

    Thank you,

    Mike
    Mike Drives:
    BMW's
    E24 - 635CSiA - (1) 1985 (US)
    E24 - 635CSi - (1) 1985 (EC)
    E31 - 850iA - (1) 1991 (Black)
    E31 - 850iA - (1) 1991 (Calypso Red)

    E32 - 740iA - (1) 1994
    E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
    E32 - 735iL - (2) 1990
    E32 - 750iL - (1) 1990

    E38 - 740iLA - (2) (1) 1997 & (1) 1998
    E38 - 750iLA - (1) 1998
    E38 - 740iA - (1) 2000 "Short Sport"
    E39 - 528iA - (2) - 2000 & (1) 1997
    Also:
    2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
    2014 Dodge Dart Rallye (Daily Driver)
    2007 Mercedes Benz CL600 (Brabus SV12S)
    Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
    1967 Buick Riviera (2)

  15. #15
    Join Date
    Dec 2009
    Location
    Gardendale, AL USA
    Posts
    306
    My Cars
    1995 840 Ci, 1959 Sprite
    I think Scott is under EE DEGREE TO DRIVE.

  16. #16
    Join Date
    Mar 2011
    Location
    Damascus, Maryland USA
    Posts
    1,548
    My Cars
    E31/E32 VWs Tesla
    Yup! I'm still here!

    In general, a General module w/ original 20 yr old capacitors simply won't work properly. The capacitors in the GM have literally been powered since the car was first assembled, they're tired and dried up. First symptom is that it kills batteries because it doesn't go to sleep and or won't start up properly when cold (so no locks, windows, interior lights, etc).
    Once the battery voltage gets too low, the GM starts a reboot loop: powers up, engages a relay, the resulting current draw pulls voltage down, GM reboots... About every 2 seconds until the battery is completely dead.

    As far as batteries go, folks LOVE to throw batteries at these cars. It's the only thing some folks know how to do. The longer batteries sit in a discharged state, the more they sulfate. Sometimes this sulfation can be reversed by the correct kind of battery charger. Then folks put new batteries in, and months later, the batteries are dead again. The bottom line is fix the underlying problem, and if your batteries are flat, charge them immediately to prevent permanent damage.

    '89 735i, '91 850i, '81 MB 380SLC (For Sale), Tesla Model 3, and VW Passat TDI -- Yes, I still repair General Modules, DM for info!

  17. #17
    Join Date
    Feb 2015
    Location
    Kuna, Idaho
    Posts
    736
    My Cars
    Too Many Cars (NOT!)
    Update:

    Replaced repaired GM. Thank you Scott! Relay no longer cycles and has been replaced with new, trunk light works, electronic trunk opening does not.

    Drivers side door and quarter windows go up and down.

    Passenger side door and quarter windows do not.

    Neither side does the window drop.

    All fuses have been checked good and sockets have correct amperage fuses.

    So, what am I missing. I would suspect the microswitch in the door for the handle if only one door did not drop, but neither drops.

    As for the passenger windows not going up or down, I'm kind stumped. I don't know if that's the same thing as the window drop. Then there's the trunk release.

    Really stretching, but seat/window memory module???

    Argh!
    Mike Drives:
    BMW's
    E24 - 635CSiA - (1) 1985 (US)
    E24 - 635CSi - (1) 1985 (EC)
    E31 - 850iA - (1) 1991 (Black)
    E31 - 850iA - (1) 1991 (Calypso Red)

    E32 - 740iA - (1) 1994
    E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
    E32 - 735iL - (2) 1990
    E32 - 750iL - (1) 1990

    E38 - 740iLA - (2) (1) 1997 & (1) 1998
    E38 - 750iLA - (1) 1998
    E38 - 740iA - (1) 2000 "Short Sport"
    E39 - 528iA - (2) - 2000 & (1) 1997
    Also:
    2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
    2014 Dodge Dart Rallye (Daily Driver)
    2007 Mercedes Benz CL600 (Brabus SV12S)
    Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
    1967 Buick Riviera (2)

  18. #18
    Join Date
    May 2019
    Location
    Grovetown, GA
    Posts
    777
    My Cars
    1991 850i 6-speed

    Got A Weird One - At Least I Think So! Lights & Trunk...

    Quote Originally Posted by masbury View Post
    Update:

    Replaced repaired GM. Thank you Scott! Relay no longer cycles and has been replaced with new, trunk light works, electronic trunk opening does not.

    Drivers side door and quarter windows go up and down.

    Passenger side door and quarter windows do not.

    Neither side does the window drop.

    All fuses have been checked good and sockets have correct amperage fuses.

    So, what am I missing. I would suspect the microswitch in the door for the handle if only one door did not drop, but neither drops.

    As for the passenger windows not going up or down, I'm kind stumped. I don't know if that's the same thing as the window drop. Then there's the trunk release.

    Really stretching, but seat/window memory module???

    Argh!
    It’s more than likely the switch that’s clipped to the back of the glove box lock.
    You can gain access to it by dropping the lower glove box.
    When the glove box lock cylinder is turned it engages the switch, and locks out the electronic trunk release when engaged or disengaged, I forget which.

    Or just turn the key in your glovebox and try the trunk again

    Sent from my iPhone using Tapatalk
    Last edited by petejk; 02-28-2021 at 05:02 PM.

  19. #19
    Join Date
    Feb 2010
    Location
    Hampshire UK
    Posts
    8,867
    My Cars
    99 840ci Sport Indv
    For the latch switches - get in the car and wait for the interior lights go out - and then try opening a door - if the interior lights come back ON then the dorr latch switch is working
    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


    My BMW Repair YouTube Channel
    My Current 840ci Sport Individual
    My Current 650ci Sport Individual
    My E31 Repair and Information Website
    My E38 Repair and Information Website
    My E63/E64 Repair and Information Website

    Chase - Heroes to a generation

  20. #20
    Join Date
    Aug 2019
    Location
    Tujunga, CA 91042
    Posts
    771
    My Cars
    850CI740Lsezd750L95sezd
    Quote Originally Posted by petejk View Post
    It’s more than likely the switch that’s clipped to the back of the glove box lock.
    You can gain access to it by dropping the lower glove box.
    When the glove box lock cylinder is turned it engages the switch, and locks out the electronic trunk release when engaged or disengaged, I forget which.

    Or just turn the key in your glovebox and try the trunk again

    Sent from my iPhone using Tapatalk
    I vote for this option. This mode is called VALET. When you lock your glove box it keeps the Valet attendant from opening anything but the driver door and turning on the ignition. You would lock your valuables in the trunk and give the valet the valet key. The valet key won't open the glove box.

  21. #21
    Join Date
    Mar 2011
    Location
    Damascus, Maryland USA
    Posts
    1,548
    My Cars
    E31/E32 VWs Tesla
    For the passenger side woes, the passenger door module may be bad, or more specifically/likely, the wires in the door hinge that allow the door module to talk to the general module may be broken. You'll want to find some diagnostic software and see if you can do realtime readings of the GM/door module, including verifying you see a state change when grabbing the handle on the inside, outside, pushing the buttons, etc.

    Passenger window should operate under 4 & 1/2 conditions:
    passenger window button
    passenger window button from driver's door
    opening door from inside or outside
    holding door key in the lock/unlock position for 10sec, which is how you roll up your windows without getting in the car

    '89 735i, '91 850i, '81 MB 380SLC (For Sale), Tesla Model 3, and VW Passat TDI -- Yes, I still repair General Modules, DM for info!

  22. #22
    Join Date
    Nov 2009
    Location
    Fredericksburg, VA
    Posts
    21
    My Cars
    1991 BMW 850i
    HYPER is the guy with the door fix parts.

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