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Thread: Passenger seat occupancy matt sensor bypass

  1. #1
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    Passenger seat occupancy matt sensor bypass

    I have a problem in the above sensor, i tried to build the bypass but i don't know where to install it. When i disconnected the cable it reveals two ends, which end i should connect the bypass to? I attached to this side of the cable but didn't work. Please advice.

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  2. #2
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    Please advice, the airbag light is killing me.

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  3. #3
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    logical thinking will tell me that the bypass shud be connected in place of the mat....ie connect to the car side of the connector....

  4. #4
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    Quote Originally Posted by moots View Post
    logical thinking will tell me that the bypass shud be connected in place of the mat....ie connect to the car side of the connector....
    +1 Then get the SRS reset or check for other problems.

  5. #5
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    take the blue and white wire connector that plugs into a control box at the rear center of the seat and unplug it then cut the blue and white wires with a few inches of slack left.

    Solder the blue and white wires to your bypass circuit and then plug the connector back into the control box on the underside of the seat and then get your airbag light reset.

    Just did this so I know this works.

    -Anson
    1999 BMW 540i Sport

  6. #6
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    I mean you can not make a mistake, the bypass replaces the mat which is under the seat bottom cover, and it comes from the seat underneath and connects to the airbag seat occupancy control unit, the black box. Simply unglug it, plug in the bypass, the reset the code.
    I hope you did a diag before and that you are sure this is the actual fault.

  7. #7
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    '98 528i 98k 5-SPP
    This bypass circuit thing....is this something you buy and then tap it into the
    wiring that you speak of?

  8. #8
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    1998 528i 5-spd 102K
    I did this a while ago....the DIY Passenger Seat Emulator.

    Bought the BMW Passenger Airbag Seat Sensor Mat Occupancy Bypass Emulator from ebay seller radzos from Vilnius, Lithuania; $10 + $5 shipping = $15 total.

    It is a very simple fix:

    1. Open Right Rear Door and look behind the Front Passenger Seat.
    - Cable that goes to SRS Computer is Blue.
    - The other connector goes to the seat sensor (Red).

    2. Unplug the factory connector (squeeze the side tabs and pull) and install this "Emulator".
    Then zip tie the factory cable so it does not hang down.

    Done in 5 minutes.
    Then use appropriate software to erase the SRS dash light.






  9. #9
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    I also purchased the pass simulator by-pass, just like CNN. for now the real stuff is working, but I have it just in case. Have it a drawer for over a year now, collecting dust.
    Looking for a DIY? Parts? Check this out, it might be your ticket

    Stable: e92is, e53 N62, e46M54B25, Tribby & e39 M54B30 R.I.P.

  10. #10
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    I used the bypass device last august, and had a shop clear the airbag light. Has been working fine for over a year.

  11. #11
    Join Date
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    My airbag light will not go off after a code reset via INPA. It's also NOT throwing any codes to begin with, just the airbag light itself.

    Could this be worth trying?
    BMWCCA #164901
    Current Rides:
    '12 X5 xDrvive35i
    '07 Aprilia Tuono Factory

    Past rides:
    '00 540i 6spd,'88 750iL,'88 735i,'79 320i,'and 78 Suzuki GS750

  12. #12
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    Quote Originally Posted by EditTim View Post
    My airbag light will not go off after a code reset via INPA. It's also NOT throwing any codes to begin with, just the airbag light itself.

    Could this be worth trying?
    I don't believe you
    Go to SRS module > Errors

    Take a screenshot and post please

  13. #13
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    Quote Originally Posted by DHoang View Post
    This bypass circuit thing....is this something you buy and then tap it into the
    wiring that you speak of?
    I built the bypass for 2 dollars in parts.

    it takes two 100 ohm resistors and a diode thats it simple.

    or you can buy a premade one.

    -Anson
    1999 BMW 540i Sport

  14. #14
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    Quote Originally Posted by BMWPlanetDude View Post
    I don't believe you
    Go to SRS module > Errors

    Take a screenshot and post please
    Fair enough. I'll need a day or two before I can get to it...
    BMWCCA #164901
    Current Rides:
    '12 X5 xDrvive35i
    '07 Aprilia Tuono Factory

    Past rides:
    '00 540i 6spd,'88 750iL,'88 735i,'79 320i,'and 78 Suzuki GS750

  15. #15
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    Its working now. I installed the bypass to the wrong cable end.

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  16. #16
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    Quote Originally Posted by mfraij View Post
    Its working now. I installed the bypass to the wrong cable end.

    Sent from my iPhone using BF.com
    You do not install the sensor to any cable end but to the control unit, which is black box.
    Is that what you meant?

  17. #17
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    Sep 2012
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    When you disconnect the sensor cable it will give two ends one is going to the sensor and one is going to the control box. I can't see under the seat to check which one is going to the control box, so the first time i installed the bypass it was connected to the end going to the sensor that is why it didn't work. Second time i installed to the other end which is going to the control box and now working 100%.

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  18. #18
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    I thought my pics above showed very clearly where to attach the bypass emulator.

  19. #19
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    Quote Originally Posted by cnn
    I thought my pics above showed very clearly where to attach the bypass emulator.
    I didn't see the pictures. My browser have a problem and not showing pictures.

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  20. #20
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    Quote Originally Posted by Alpina540i View Post
    take the blue and white wire connector that plugs into a control box at the rear center of the seat and unplug it then cut the blue and white wires with a few inches of slack left.

    Solder the blue and white wires to your bypass circuit and then plug the connector back into the control box on the underside of the seat and then get your airbag light reset.

    Just did this so I know this works.

    -Anson
    Pardon my ignorance but what if you disconnected the battery before disconnecting the sensor...would the airbag light still come on after the bypass install? I'd rather not have to pay to have it reset.
    German Engineering, Astounding Ingenuity, Over 9 Decades of Conceptual Continuity

  21. #21
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    If you don't have a airbag light on then you can avoid triping the light by disconnecting the battery.
    1999 BMW 540i Sport

  22. #22
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    Quote Originally Posted by Alpina540i
    If you don't have a airbag light on then you can avoid triping the light by disconnecting the battery.
    It's better to disconnect the battery before removing seat cables, door mat cables... Etc or anywhere you have airbag to prevent triggering the air bag light which will need special tool for error resetting.

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  23. #23
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    Quote Originally Posted by BMWPlanetDude View Post
    I don't believe you
    Go to SRS module > Errors

    Take a screenshot and post please
    Here are pics of my xp laptop connected via 20-pin round connector under the hood. I've had no problems resetting codes for when they do pop up with this set up (INPA on a windows xp w/ serial connection). Prior to this, I had another forum member attempt to reset the airbag light with a Peake tool, but was unsuccessful.

    In this series of pics, the error memory report screen shows no codes found. Resetting the code memory doesn't do anything since there is no code to clear. Final pic is the airbag light blazing away in all it's glory on my dash...
    Attached Images Attached Images
    BMWCCA #164901
    Current Rides:
    '12 X5 xDrvive35i
    '07 Aprilia Tuono Factory

    Past rides:
    '00 540i 6spd,'88 750iL,'88 735i,'79 320i,'and 78 Suzuki GS750

  24. #24
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    e39 '98 540i6, 2007 B7
    reviving the dead here...so this turns off the airbag light but how does it affect the passenger airbag operation? Does it just assume it is occupied at all times and therefore will deploy the airbag? Or it is the opposite, assumes the seat is empty and will never deploy airbag?
    1998 (9/97 production date) 540i 6 Speed Sport / black on black / shadow trim / debadged / black-out grill / Carbon fiber roundels / 80w Yellow Fogs / 2.81 non- lsd diff. / 17" BBS Sport Style 19 wheels/ 245 all around tires / modified CDV / Stage I Dinan software / 5w30 synthetic/ 244k miles and counting

    E65 2007 Alpina B7: Black on Black, Supercharged autobahn eater, 500hp/515trq, 245/295 tires, 141k miles with major systems rebuilt/replaced!

  25. #25
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    My light was on so I bought one of the mat emulators and went to install it. Don't see the proper connection under my pass seat. One pic shows the front edge underside with a few large 2 pin connectors but totally different than the emulator. The rear of the seat has the black box with a small 3 pin connector in it. In the 3rd pic, this is the connector.

    I had this mat sensor replaced by an upholstery shop several years ago. I wonder if they used a different sensor although I can make out "bmw" on the black module and some lettering.

    While I was at it, I cleared the codes and no airbag light now. I'll drive it a bit and sit in the pass seat and see if it comes back.

    Otherwise, am I missing something or do I maybe have a different sensor and therefore need a different emulator? Thanks.



    540 under pass seat rear module.jpg540 under pass seat front.jpg540 seat sensor connector.jpg
    1998 (9/97 production date) 540i 6 Speed Sport / black on black / shadow trim / debadged / black-out grill / Carbon fiber roundels / 80w Yellow Fogs / 2.81 non- lsd diff. / 17" BBS Sport Style 19 wheels/ 245 all around tires / modified CDV / Stage I Dinan software / 5w30 synthetic/ 244k miles and counting

    E65 2007 Alpina B7: Black on Black, Supercharged autobahn eater, 500hp/515trq, 245/295 tires, 141k miles with major systems rebuilt/replaced!

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