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Thread: 1991 850i alarm issues

  1. #1
    Join Date
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    1991 850i alarm issues

    I was quazi-gifted a 1991 850i. Beautiful car, but the alarm/security system is insane.

    1) When I got the car, factory alarm was disabled (fuse previously pulled from alarm module), and an after market alarm was installed. I honestly can't see the how the after market alarm is attached to car anywhere except power and the antenna wires to the receivers in front/back of the car. The after market-alarm box was stuck beneath the steering wheel. Could it enable the starter wirelessly? The car tried to start once, but when I replaced the batteries I can't get it to turn over at all. No one has a FOB for the aftermarket alarm.

    2) the instrument cluster does not function UNLESS I reinsert the fuse for the alarm module, but then, of course, the alarm is enabled and presumably, both alarm systems are activated. I can't seem to disable the alarms at all. Turning the key in the driver door does nothing. The key has a new battery, but it doesn't seem to communicate with the car at all.

    3) I shorted the micro-switches in the driver door to simulate the key unlocking the door (try to turn off the alarm), but this doesn't seem to do anything either.

    I'm at a loss. Is there any way to disable the alarm and allow the car to start so I can try to get this car put back together? Any advice or links are appreciated.

    I'm in Logan, Utah.

  2. #2
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    You can bypass the remote start by removing the plug between the ignition and the aftermarket alarm, Then reassembling the oem wiring in the ignition area, I hope you installed your new batteries by fixing the Positive cables first on both sides and then the negatives.

  3. #3
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    the after market alarm does not seem to intersect any of the factory wiring. . there is no "plug" I can find. That's why I'm asking if the after market alarm system could be allowing starting wirelessly?

    Also, I'm pretty sure I installed the batteries one at a time (pos/neg to bat1 ,then pos/neg to bat2). what would happen if I did it wrong?

  4. #4
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    btw, I have a working key and the light (on the key) goes on when I push buttons, but it doesn't ever seem to evoke a response from the car. I can unlock the door and turn the ignition mechanically, just alarm goes off as soon as I turn the key and no start.

  5. #5
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    There is no wireless alarm to start that car, Maybe you had a starter issue from the beginning where you said it tried to start itself? Does the starter get power when the ignition is in the start position?-------------The batteries have to be connected, Both Positives on both sides first and then both negatives, If not it could effect your oem alarm and not start because it is armed. Disconnect both Negatives and then both positives, Wait 10 minutes and connect both Positives and then both negatives and see if things change.
    Last edited by 8eights; 01-14-2019 at 12:14 PM.

  6. #6
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    Awesome. Thanks. I am not trying to start the car wirelessly. I have the key. Just whenever I turn the ignition on (with the key), the alarm goes off. I presume that's why it is no starting. I can't imagine why connecting the batteries that way would effect anything, but I'll try it anyways.

    The trunk, hood, and passenger door all set off the alarm, but the driver door does not. It's possible that the alarm doesn't know I've entered the vehicle and disables the starter because it senses the ignition going on without turning the alarm off. I really believe I just need to turn off the alarm first.

  7. #7
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    You just need to re-program your keys as described below:

    https://www.meeknet.co.uk/e38/Key_Program.htm

    Sent from my SM-G935F using Tapatalk
    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
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    The links says how to program a second key. I only have one key, but I will try it anyway. Thx.

  9. #9
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    The alarm can also be defeated by (at most stages the alarm sounds - ignore it):

    Lock the car with the key from the drivers door
    Unlock the drivers door with the key and get in
    Shut the door behind you and make sure all windows are up, bonnet and boot shut
    Put the key in the ignition to position I (accessories)
    Sit there and don't fiddle with anything for up to 15 minutes
    At some point the alarm light will go out and you should be able to start the car

    This is not some secret method - it's in the Owners Manual
    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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  10. #10
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    I've done that a few times with no luck, but it's possible the trunk or hood was not shut. I'll try again. Is there any way to be sure the computer thinks everything is closed?

    Should the passenger door lock when I lock the car from the drivers door? I don't really see any response from the car when I lock/unlock the driver door.

    Oh. . and also, the alarm doesn't sound when I open the driver door (it does with all other doors/hoods), so I'm guessing the computer doesn't know that the driver door is closed or open. . I'll check those as well.

    THANKS for all the help!
    Last edited by protonspring; 01-14-2019 at 06:17 PM.

  11. #11
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    I found a few blown fuses. After replacing them, the key now successfully arms/disarms the alarm in the master cylinder. I couldn't tell which one it was, but apparently one of the fuses provided power to the driver door. Now things seem to be working normally and the car STARTS! Fun fact: When I turn the key all the way left and hold, all of the windows roll down! First sign of life and such a cool feature.

    Question. After disarming the alarm, I wanted to disable it permanently, so I removed the fuse from the alarm module. However, when I do that, the instrument cluster stops working (just the odometer and dials). Is there a way to permanently disable the alarm system and still have a functioning instrument cluster?

  12. #12
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    Smile

    ...yes, Check all your fuses first!.)

    J/K

    Both my cars have oem alarms disconnected and the clusters work fine.

  13. #13
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    Any idea how you disconnect the alarm module so that the cluster still works?

  14. #14
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    I only pulled the blue fuse in the photo.
    Attached Images Attached Images

  15. #15
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    Yep. . that's what I do. . When I do that, the odometer lights go out on the cluster, and the gauges stop working. I'll check again. . . maybe I'm crazy.

  16. #16
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    i verified this. With the car on, when I pull the fuse from the alarm module, the odometer values go out, but the backlights stay on.
    With the car off, when I pull the fuse from the alarm module and turn the car on, the odometer display is blank ( no values or backlights).

  17. #17
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    On the early models that fuse also supplies power to the Body Electronics module via the RED/GRAY/YELLOW wire - you could try linking RED to that wire on X335:

    https://www.meeknet.co.uk/e31/e31_91.pdf#page=329
    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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  18. #18
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    That worked perfectly. Connecting RED (power) to the Red/Gray/Yellow wire on the X335 connector powers the display.

    As far as I can tell, the aftermarket alarm is removed and the factory alarm is permanently disabled with no other side effects.

    Thank you TIMM!

  19. #19
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    My pleasure - but this just disconnects power to the siren and the horns - the rest of the alarm module is probably doing something!
    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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