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Thread: Airbag ECU replacement

  1. #1
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    1999 BMW 540iA

    Airbag ECU replacement

    Here's a DIY about airbag control unit replacement. I had the airbag light on in freezing temperatures. With INPA I got the following error: 240 Internal ECU error, which requires the airbag control module to be replaced

    DISCLAIMER: I take no responsibility for damages to you or your car. Follow these instructions at your own risk.

    Tools needed:
    7mm socket
    10mm socket
    1/4" extensions
    1/4" ratchet
    screw driver
    NCS Expert

    1. Remove the battery negative cable.

    2. To remove the rear cup holder lift up the rear vent (1) and pull the cup holder (2) out.

    joNk3lQ.jpg

    3. Pull down the rear vent (1) and remove.

    4. Remove the two screws and two nuts circled in red.

    j4hgQzT.jpg

    5. Remove the armrest and the tray under it.

    6. Remove the two easily accessible nuts holding the airbag control module.

    LWVHEc2.jpg

    7. The third is a bit tricky to get to. It can be access via the hole circled in red. In the first picture you can barely make out the nut. In the second I've pushed the rear air duct to gain access to the nut. Any of my sockets didn't fit through the hole so I had to put the extension through it and then install the socket on it inside the center console. A bit tricky to do, but not too bad.




    xOvOioM.jpg



    8. Remove the Airbag ECU connector. This type of connector is used in number of places on your e39. You'll need to pull the green locking clip towards the rear of the car to release it. If you want to practice how to do it you can find similiar connector on Cd-changer, NAV computer etc.

    9. Take out the old Airbad ECU and install the new one. Remember to put back the grounding wire under the nut (1).

    10. Assemble everything back together. To install the third nut put a piece of paper between the socket and the nut so the nut won't fall off.

    11. Code the new Airbag ECU. I did this with NCS Expert. A great how to code with NCS expert can be found here. Download the HOW TO CODE WITH NCS EXPERT.pdf
    Last edited by Spirit Force; 12-02-2015 at 11:01 AM. Reason: Uploaded the images yet again, this time hopefully for good.

  2. #2
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    Anybody got any comments?

  3. #3
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    2000 528i
    Hey Spirit Force,

    I have the same issue with my 528i. Airbag light on when it's cold in the morning. Can tell me the BMW part number? I have the Temic Part number of 060900727 but it is getting me nowhere. I can read the same fault code using Bravarian Technics Reader but the version I have will not code units. Where can I get the cable and software for the NCS Expert? Thanks!!

    I forgot to say excellent DIY and pictures! My Bimmer is a 2000 with M Sports Suspension.
    Last edited by DrAV; 01-19-2013 at 04:59 PM. Reason: Automerged Doublepost

  4. #4
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    Where did you get that part number? The BMW part number should be 65 77 6 900 727 according to bmwfans.

    You can get the cable on ebay for ~$20-60. You'll need the usb OBD2 and the OBD2 20 pin adapter. The price depends on how fast you want it. The software can be downloaded for free. You should head to the diagnostic sub-forum, because there's ton of information about diagnostic tools. NCS Expert is part of EDIBAS. You'll need cables like these:

    USB OBD2
    20 pin to OBD2 adapter

    The airbag control module can be fixed, but I opted not to get it fixed because a) used control modules are cheaper than getting it fixed b) I didn't want leave the car sitting while waiting for it.
    Last edited by Spirit Force; 01-19-2013 at 06:34 PM.

  5. #5
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    Finally found the BMW part number under RealOEM in the Navigation and Radio Sub-section go figure! Thanks for finding it out for me also, I appreciate the effort. I'm sort of handy with a soldering iron and around electronics and I understand a lot of the failure issues in modules like this is cracking of solder joints due to thermal cycling. Makes kind of sense that it only shows up when it's cold and the parts are contracting, that would open a crack up and cause an open circuit. I might try to see if I can find a crack and if so I will post my repair. If that fails I will buy a used or new one. I'm afraid a used one will end up in the same state. Tisher BMW lists this new at ~4 bills.

    I'm always at a loss with connectors. There is virtually no space in there to reach it... how does this one come off? I see what looks like a green handle (at the connector end nearest the front of the car) over the yellow block and the block has a tab. Does the green handle get pulled back while the tab is pushed down? Thanks for your help on this! My socket fit through the hole... lucky me.

    Thanks for the link on the Cable and Software much appreciated!!
    Last edited by DrAV; 01-19-2013 at 11:19 PM. Reason: Automerged Doublepost

  6. #6
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    My link to bmwfans would have taken you directly into that part. My initial tought was also that it's a cracked soldering joint, but after some googling around I found out that the eeprom is corrupted and needs to be programmed to erase that code. Any car diagnostic tool won't be able to reset it. So the root cause might be a cracked solder joint, but fixing soldering joints won't erase the code. Besides the used modules that expensive so I didn't bother to dig deeper. I paid around $60 for a used module

    Yes, you need to pull the green handle back to release the connector. It works just like other bmw connectors so I didn't include that in the DIY. Maybe I should? The space inside the center console is very limited, but you can get a bit more room by first removing the nuts and lifting the module off the studs. However you can't pull the module out because there isin't any slack in the cable.

  7. #7
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    Yep, I did remove the unit from the studs and stopped there while waiting for an update on this forum, I didn't want to break the connector. I also found the code won't erase but that doesn't seem to affect the operation of the unit and the Airbag Light only comes on when it's cold. So I'm thinking that code is not setting the airbag light. I might be able to repair it if I want to put up with the permanent code.

    I haven't decided yet which way to go. Maybe I'll go the used route and have this unit as a spare that I can mess with. I'm probably going to delay going further until next week as I've come down with a nasty cold that the kids have. It knocked me flat last night. I'll post my progress when I get back to it but expect a delay. Thank you for all the help!

  8. #8
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    Well we can't say for sure what effect that internal error has on the airbag system in a crash so I would just replace it. I consider it a safety issue, but of course it's your choice.

    No problem feel free to ask, if there's anything else.

  9. #9
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    I downloaded INPA. During the install it asked about various interfaces... I just selected the default OBD-Can. Since your bimmer is about the same vintage 1999 vs my 2000 and the same E39 chassis was this the correct choice?

    My local BMW dealer wants 3 bills for coding a module. In Southern California there is no such thing as reasonably priced BMW service. I'm going to buy a used module and try to program the thing.
    Last edited by DrAV; 01-22-2013 at 03:10 PM. Reason: new info

  10. #10
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    You need to install EDIBAS. NCS Expert and INPA are part of EDIBAS package. I would first download a installation guide so there is no need for guessing games. You got the cables already?

  11. #11
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    i need to do this!!

    how much does the part go for used? can i diy the coding? or is it best to take it to somebody?

    how long did it take? i have had the interior of this car this far apart before, but i cant see the pictures where i am, so i cant see exactly which part your talking about.

  12. #12
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    All but one of your guestions have already been answered in this thread..

    I stated that I paid ~60$ for a used one. Yes you can DIY the coding as I did. The DIY time depends greatly on how good you are working in tight places. I would say 30-60 minutes, for me it took longer do to fact I had to stop to take pictures. We are discussing about replacing the Airbag control module.

  13. #13
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    wonderful, thank you

  14. #14
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    Quote Originally Posted by Spirit Force View Post
    You need to install EDIBAS. NCS Expert and INPA are part of EDIBAS package. I would first download a installation guide so there is no need for guessing games. You got the cables already?
    I'm about to order the cables... so I guess I'm a few weeks from doing the deed. I located a used module on E-Bay, just waiting for confirmation that I can get my money back if it has the dreaded 240 Internal ECU error.

  15. #15
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    Missing SGFAM.DAT File

    Quote Originally Posted by Spirit Force View Post
    You need to install EDIBAS. NCS Expert and INPA are part of EDIBAS package. I would first download a installation guide so there is no need for guessing games. You got the cables already?
    Got the software installed, got the cable, got a replacement ECU. Already opened my current ECU up and can't find anything obviously wrong like a cracked solder joint. So I will need to install the replacement ECU> Looks like things are working (cable and software) but when I click on the E39 Chassis in NCS Expert it gives me an error message "Cannot Open File for Reading C:\NCSEXPERT\BIN\SGFAM.DAT". When I look in the BIN folder there is no SGFAM.DAT file and I have searched all of my files and folders and cannot find this file. Can you tell me where I can get this missing file? I've searched around the forums and can't find any mention of this file. Thank you!

  16. #16
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    Quote Originally Posted by DrAV View Post
    Got the software installed, got the cable, got a replacement ECU. Already opened my current ECU up and can't find anything obviously wrong like a cracked solder joint. So I will need to install the replacement ECU> Looks like things are working (cable and software) but when I click on the E39 Chassis in NCS Expert it gives me an error message "Cannot Open File for Reading C:\NCSEXPERT\BIN\SGFAM.DAT". When I look in the BIN folder there is no SGFAM.DAT file and I have searched all of my files and folders and cannot find this file. Can you tell me where I can get this missing file? I've searched around the forums and can't find any mention of this file. Thank you!

    Hmm it would seem that there is something wrong with your install. Have you downloaded and installed a different package? This package should work, because it is mentioned in multiple install guides.

  17. #17
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    That link does not appear to be working...

  18. #18
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    Hmm just download ediabas-6.4.3-full. With google you can find it pretty much everywhere.

  19. #19
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    Quote Originally Posted by Spirit Force View Post
    Anybody got any comments?
    Step #0

    Unplug battery negative terminal

  20. #20
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    Quote Originally Posted by Spirit Force View Post
    Hmm just download ediabas-6.4.3-full. With google you can find it pretty much everywhere.
    OK, I reinstalled my package following the instructions more closely. Selected the UK Configuration as directed (why UK when I live in the US is beyond me). Success this time, except somehow NCS Expert is all in German! I was able to select the correct buttons anyhow with the procedure I was using and with some extra help from Google Translate the end result is the same. After the coding I started my BMW and the Airbag Light went off then came back on again! Drat! I repeated the coding process again and the second time all is well. When I have some more time I will probably do a third install and try to get it back to English. Thanks for all the help without it I would not have been able to do this! I took a few pictures that I will try and post in a day or so.

  21. #21
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    Quote Originally Posted by joako View Post
    Step #0

    Unplug battery negative terminal

    Good point there! I forgot to include that because I always disconnect battery before working with SRS system. Fixed that.

    Quote Originally Posted by DrAV View Post
    OK, I reinstalled my package following the instructions more closely. Selected the UK Configuration as directed (why UK when I live in the US is beyond me). Success this time, except somehow NCS Expert is all in German! I was able to select the correct buttons anyhow with the procedure I was using and with some extra help from Google Translate the end result is the same. After the coding I started my BMW and the Airbag Light went off then came back on again! Drat! I repeated the coding process again and the second time all is well. When I have some more time I will probably do a third install and try to get it back to English. Thanks for all the help without it I would not have been able to do this! I took a few pictures that I will try and post in a day or so.
    One reason to have the airbag light on after coding could be that the module came from a car that more airbags than yours. After coding I had the airbag light on. Checked the codes and found codes for rear airbags, which I don't have so I just cleared the codes and the light was gone.
    Last edited by Spirit Force; 02-10-2013 at 07:16 AM. Reason: Automerged Doublepost

  22. #22
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    Quote Originally Posted by Spirit Force View Post
    Good point there! I forgot to include that because I always disconnect battery before working with SRS system. Fixed that.



    One reason to have the airbag light on after coding could be that the module came from a car that more airbags than yours. After coding I had the airbag light on. Checked the codes and found codes for rear airbags, which I don't have so I just cleared the codes and the light was gone.
    Disconnecting the battery cable is definitely important and the first step when working on the air bag system! It's also important to do for just about any electronic/ECU system work. Good point on the extra Air Bag Codes. I didn't check that and the module worked on the second re-code so all is well. I did run a code check yesterday just to see if the replacment ABS ECU had any errors and it was clean.

  23. #23
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    In terms of disconnecting the battery; doesn't the airbag sysyem retain voltage for a period of time after loss of electricity? Is there a set period of time you should wait before unplugging the module?
    2008 X5 4.8i Sport
    2004 325xi
    2000 528i

  24. #24
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    Quote Originally Posted by RacerX5 View Post
    In terms of disconnecting the battery; doesn't the airbag sysyem retain voltage for a period of time after loss of electricity? Is there a set period of time you should wait before unplugging the module?
    Bentley says you should wait for 5 seconds, TIS 1 minute.

  25. #25
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    Just did this DIY on my E39 - 2000 528i. It was very simple. I spent last weekend reading, re-reading, and re-re-reading instructions/advice from this forum to properly set up the SW on my laptop. It took me a while, but I'm glad that I took the time. Used these links (primarily):

    http://www.bimmerfest.com/forums/sho...d.php?t=564570
    http://forums.bimmerforums.com/forum...4-step-by-step

    Bought cables for coding from Amazon. These worked for me:

    http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1
    http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

    Found a used ECU on ebay for $70. Seller in CA - very prompt and free shipping. The replacement ECU that I bought has the exact same part number and SW version as the one that went south in my car. After installing the replacement, I only had to clear error memory with INPA, no need to re-code with DIS.

    Quote Originally Posted by Spirit Force View Post
    Yes, you need to pull the green handle back to release the connector. It works just like other bmw connectors so I didn't include that in the DIY. Maybe I should?
    Yes - you should have included it Getting that connector off was the most difficult part of the whole process. I finally fashioned a tool using a paper clip, gaff tape and a tent stake to get it loose. McGyver would be proud!

    Thanks for the info you posted hear - it was a BIG help!

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