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Thread: Anyone with bad GMs or botched GM repairs? I'm interested.

  1. #1
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    Anyone with bad GMs or botched GM repairs? I'm interested.

    Two GMs that I have fixed for folks had been operated on before and the capacitor install was botched by someone...

    I have seen the following mistakes:
    --Capacitors installed in the wrong holes (no, not swapped parts, completely wrong holes!)
    --Capacitor installed with wrong polarity or Polarized cap not used..
    --Traces pulled up/broken from yanking the old capacitors out
    --Solder bridges from careless installation (too much solder at times)
    --Traces cut/broken from someone prying with their iron/slip of their hand
    --Inadequately flowed solder/cold solder joints (too weak of an Iron)

    I use a 100W solder station, fresh solder, and a solder sucker to properly heat/remove/reinstall capacitors. If you have limited soldering skills, do yourself, the next owner, and the community a favor and don't trash your GM; ask someone or pay someone for help.

    Finally-- My point:
    If anyone has a GM lying around that is damaged, or where someone botched the repair, let me know. Additionally, if you are still struggling with a battery drain issue, or have another issue that might be traced back to a bad or inadequate GM repair, let me know.

    I am interested in trying to "save" them, and would like to have 1 or 2 om my shelf.
    Last edited by EEDegreeToDrive; 09-19-2012 at 03:14 PM.

    '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!

  2. #2
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    I have some spares if needed.

  3. #3
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    it would be awesome if you had an exchange service. mail out return /deposit type deal?? probably would have saved the one i cooked.
    While you're down there ...

  4. #4
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    Quote Originally Posted by m10n View Post
    it would be awesome if you had an exchange service. mail out return /deposit type deal?? probably would have saved the one i cooked.
    I do have an exchange service... I can usually change the caps and send the same unit out the next day.

    However, I am interested in GMs sitting around that have been screwed up by bad cap installs. I wouldn't feel comfortable exchanging PersonA's screwed up GM with PersonB's virgin GM that just needs caps.

    I am mainly interested in capturing/repairing the potentially screwed up ones before they go to the landfill, and hoping to build a small inventory of spares.

    '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!

  5. #5
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    true, i didn't think about it like that. i can only advise anyone reading this to not do it yourself, and send it to a competent electronics person so you don't burn it down doing it yourself.
    While you're down there ...

  6. #6
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    Quote Originally Posted by m10n View Post
    true, i didn't think about it like that. i can only advise anyone reading this to not do it yourself, and send it to a competent electronics person so you don't burn it down doing it yourself.
    If you still have the bad one around, I'd be interested in buying it off you, obviously covering at least your shipping

  7. #7
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    i gave it to Steffen when he came out to reprogram my replacement.
    While you're down there ...

  8. #8
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    Quote Originally Posted by EEDegreeToDrive View Post
    Two GMs that I have fixed for folks had been operated on before and the capacitor install was botched by someone...

    I have seen the following mistakes:
    --Capacitors installed in the wrong holes (no, not swapped parts, completely wrong holes!)
    --Capacitor installed with wrong polarity or Polarized cap not used..
    --Traces pulled up/broken from yanking the old capacitors out
    --Solder bridges from careless installation (too much solder at times)
    --Traces cut/broken from someone prying with their iron/slip of their hand
    --Inadequately flowed solder/cold solder joints (too weak of an Iron)

    I use a 100W solder station, fresh solder, and a solder sucker to properly heat/remove/reinstall capacitors. If you have limited soldering skills, do yourself, the next owner, and the community a favor and don't trash your GM; ask someone or pay someone for help.

    Finally-- My point:
    If anyone has a GM lying around that is damaged, or where someone botched the repair, let me know. Additionally, if you are still struggling with a battery drain issue, or have another issue that might be traced back to a bad or inadequate GM repair, let me know.

    I am interested in trying to "save" them, and would like to have 1 or 2 om my shelf.
    Scott,
    You will be doing mine when I need it.
    Just letting you know.

  9. #9
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    1991 BMW 850i
    Thanks for the info. I just re-did my caps on the A1 board and now for the first time in a long long time the car is working as it should. Yay! Key is to use a hot iron since you have to solder both sides of the board at the same time.

  10. #10
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    Wink

    Scott, I have a 1995 840CI that I am having a great deal of trouble with. I have read your posts about the GM . Where is it located so I can pull it and send it to you. I live in California, Maryland. Thanks niko01 ( Nick Vanikiotis)
    Last edited by niko01; 09-28-2012 at 02:46 PM.

  11. #11
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    Quote Originally Posted by niko01 View Post
    Scott, I have a 1995 840CI that I am having a great deal of trouble with. I have read your posts about the GM . Where is it located so I can pull it and send it to you. I live in California, Maryland.
    Not usually a good idea to post full contact details in the forum; automated internet bots will capture it and spam you. Go back and edit it.

    Anyway-- The GM is behind the driver's side knee bolster (below the steering wheel) It is in a cartridge with 2 other modules (the ZKE and the RM).

    If you are a small guy, you can lie on your back, disconnect the 3 modules, and drop the entire assembly. It takes about 5-10 minutes and requires a 1/4" drive socket, some extensions and a flashlight. Reinstallation is reverse of installation.

    If you are of the larger persuasion, or can't lie on your back in the driver's footwell, you can remove the knee bolster (and same other trim), exposing the 3 modules, and then just remove the module of interest (should be the middle one IIRC). This method may be easier, but I haven't had any trouble doing it the other way.

    I am sending you additional details in an EMail. Forum rules prevent me from offering services.
    Last edited by EEDegreeToDrive; 09-23-2012 at 12:22 PM.

    '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!

  12. #12
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    1991 BMW 850i general module

    I have a general module available. Please contact me via e-mail direct...
    johnescott2nd@cox.net. Thanks...

  13. #13
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    Quote Originally Posted by johnescottii View Post
    I have a general module available. Please contact me via e-mail direct...
    Do you like Spam? I sent you an EMail, but for reference, posting email addresses in a forum is bad, because spam/web crawlers will harvest your EMail address.

    Go back and edit the post to delete your EMail.

    If you MUST put an email in a public place, use something like...
    myemail123 at gmail dot com
    to obfuscate the address.
    (Although, I'd could probably write a pretty intelligent web crawler to make sense of many of these obfuscations...)

    '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!

  14. #14
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    Quote Originally Posted by EEDegreeToDrive View Post
    Finally-- My point:
    If anyone has a GM lying around that is damaged, or where someone botched the repair, let me know. Additionally, if you are still struggling with a battery drain issue, or have another issue that might be traced back to a bad or inadequate GM repair, let me know.

    I am interested in trying to "save" them, and would like to have 1 or 2 om my shelf.
    I do the same thing in the UK.

    Not all car mechanics are also electronic engineers so you do come across some interesting repairs from time to time...

  15. #15
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    Gold Coast ausralia
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    I have this problem on a 95 840i it appears the 2 green relays in the boot are left on they seem to be connected to cabin lights boot light and possibly the heater valves. I’ve tried replacing the capacitors but that hasn’t cured it what’s your email so I could arrange to send it to you for checking or is there anyone in Australia who could do this ? Cheers

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