Is it faulty module or a short circuit? Electrical help needed

    Please forgive the long post.
    Hello, I’m from the US and new to 8 ownership. I just got a 97 840 and I’m dealing with some electrical issues and need help. I’m posting here on the 8er forum with the hope that some of the many electronics experts (Revtor, Reinhardt, 8tech, Timm, et al.) will be willing to point me in the right direction. In the interest of full disclosure I wrote a similar post on Bimmerforums. I posted here when I realized that some of the guys I found most knowledgeable are on this forum. I hope I've posted this is in the right forum.


    Symptoms:

    • ¨ The following items are energized at all times (with or without key in ignition): MID, Odometer and trip odometer readings, mirrors, radio, seats, steering wheel adjustment, wipers. Interior lights in automatic mode work but no delay upon exit.



    • ¨ Central locking with key fob is not working. I can lock doors and trunk (but not gas fill door) with key at driver's door. I can lock the trunk from the glove box.
    • ¨ Excessive power draw and no cut off my Relays 72 &73. Both relays are constantly energized and hot to the touch.



    Right now I am concentrating on the constant power problem and I suspect that the excessive power drain is related to the constant on situation. I’ve read many posts regarding the odo light staying on or going on and off intermittently but none mentioned the constant power to the Mid, radio, odo. So my situation may be different—perhaps a short?


    Here's what I've done so far:
    I had both the GM and RM refurbished by EEdegree, one of the Bimmerforums, members. He’s done a lot of these and is highly skilled at it. He also helped get me started with diagnosis.


    New batteries.

    Did the 16 min test, never powered down, amp draw remained same, and relays 72 and 73 consumer cut off relays remained hot and energized.


    Disconnected the ignition switch, Mid, Radio etc remained powered.

    Disconnected the MID – Mid, Radio etc remained powered


    Pulled all fuses one at a time with the only change being a loss of power where it would individually be expected for example radio, or odometer (fuse 1) but other items still remained powered.

    Special Note: When I pull fuse 43, which as I understand it fees power to the RM; all the constantly powered items are no longer powered and behave normally. The odo goes out and stays out after turning off the key and exiting, the radio, MID and widows, etc are powered only when key is in acc or run. Of course I loose other functions like the widow drop down on exit and entry.

    Pulled all colored relays, bench tested for working as designed, check pin assignment against ETM. All functioning as designed but no change in the constant power situation. Pulled the consumer cut off relays, no change. As I noted previously there is constant voltage at pin 4 and 8 of relay 72.


    Disconnected all switches in the driver and passenger door for locks and handles and disconnected the door modules, no change in the constant power.


    Disconnected X42 in the EKM as suggested by Omega man. Odo went out but other items stayed powered.


    My guess is that it is either a short of a hot and run on acc wire(s) or one of my modules (GM, RM, EKM or other) is creating a situation that is constantly feeding the MID, Radio, Odo, etc. I am at a loss on what to do next. The thought of taking it to the dealer is painful.



    I appreciate any help you can give me.

    Hello and welcome,


    looks like you´re having a rough start. I read through the thread on Bimmerforums.com and you´re in the best of hands already ;)


    Zitat

    Special Note: When I pull fuse 43, which as I understand it fees power to the RM; all the constantly powered items are no longer powered and behave normally.


    I´d have a closer look here and take out GM/RM again to check connectors for bent pins. Have seen pins bent down to contact others thus creating a short.
    Loan a RM/GM from a reliable source (Tom Carter aka Wuffer can certainly help, likely also Steffen or Greg in TX) to exclude possibility of lower lying malfunction not fixed by replacing caps.


    Replacing EKM without also swapping cluster is not as simple - you´d require coding soft- and hardware to make it work with your current instrument cluster and also see to it that the ZCS coding matches.


    The outcome is interesting for everyone - also here, so thanks already if keeping us updated.


    Reinhard


    PS: do you know what kind of work was done prior to your purchase?
    There was another thread where similarly strange power phenomena appeared shortly after installing a new heater core and last I remember were blamed on a set of wires running behind the heater core in the dashboard.

    Reinhard (sorry for the misspelling in my op) Thanks for your response. I'll check the pins on the GM/RM as you suggest and I'll reach out for the guys you noted. Also with respect to the EKM I came across this exchange between Omega man and Revtor which would seem to indicate a possible solution to a used or "unmatched" EKM if it turns out to be the EKM:


    Originally Posted by Omega man 1969 6/10/14



    Zitat

    Revtor am I correct in thinking if I whip that 93c56 EEPROM out and stick it in a used EKM I will keep my mileage ? I have a de-soldering station, it will only take me a few minutes.


    Revtor:


    Yes, that will work!



    Without getting ahead of my self I've made a note to follow up on this fix as I have access to someone that could make the chip swap but I have no knowledge of the software that is used to fix a mismatched EKM and cluster problem. Are you familiar with the EEPROM swap?


    If either Revtor or Omega read this perhaps they could comment. I note that the swap fix seems to be in conflict with a write-up on cluster swap located here: http://e31wiki.org/wiki/Instrument_cluster_swap


    I have some repair records but none show any heater core or dashboard removal. I will certainly keep the board posted on any progress.


    Thanks

    That's funny because I wrote both that reply to Omegaman and the E31Wiki article... Now I have myself confused :hmmmm:. It's been several years since I looked into this but at the moment I can't think of a good reason why swapping the EEPROM wouldn't work. Anyway, you can try another EKM without recoding or swapping the EEPROM. The gauges will remain dead and the odometer will read EEEE, but other than that it is fully functional. So if you suspect the electrical issue is caused by the EKM you can test it this way.


    Anyway, Timm posted some good advice to your thread over at bimmerforums.com (link). First try to isolate what is causing the issue.

    I didn't know you wrote both:laugh:. I'm glad you responded though and I agree I need to confirm the source of the issue first. A question for the moment: Given the capability of the software and diagnostics that you are familiar with is it possible to test the functions and communication of the various modules (GM, RM, EKM) to determine if they are working properly? I've read of a number of guys swapping out GM and RM, ect for testing and I was wondering if that was because that's the only way to test or if it's because limited access to the computerized diagnostics. I'll update this post with any progress I make with Timm.


    thanks

    While I do believe that every BMW enthusiast should have a DIS, ISTA or INPA diagnostic system, don't expect wonders from it. In some cases it directly pinpoints the problem and in other cases it may hint at where to look, but quite often no relevant fault codes are stored at all. So sometimes it's just quicker to simply swap the suspected module. In this particular case I really have no idea whether diagnostics could be helpful. Both the EKM and GM do have a basic self-test that stores a fault code when it fails, but I'm not sure exactly what it covers. For the EKM there's even a special self-test function in DIS and ISTA, but again I do not know what it covers.

    With considerable help from Timm and many others, I was able to track down the cause of all my electrical issues in one shot.


    Timms suggestion to focus on the fuse 18 circuit was spot on. I determined that the circuit was being back-fed by a hot at all times source and through the process of elimination I tracked it to the passenger side make-up mirror and light. It turns out that a PO had spliced the hot at all times wire from the sunroof module to the fuse 18 circuit in order to power the mirror light. That in turn back-fed the circuit and powered everything on it at all times. I broke the splice and put it all back together and my odo, windows, radio, etc., all worked as it should. I am one happy camper!


    A small piece of collateral damage did occur in that the steering column memory is not working now whereas it was working prior to my taking everything apart. The steering column memory module was one of the consumers on the fuse 18 circuit and, as I worked through my issues, I disconnected it to test the circuit . I know I re-connected it but I must have done something wrong. The good news is that I can enjoy the car for a while and tackle the steering memory issue in due course.


    When I originally posted here I hoped that I would get the benefit of the members of this board and I did--big time! If you are interested in the details see the link below. If for any reason you have interest in the details and do not find what you want at the Bimmerforums link just let me know and I will be happy to help. I realize that this was not the more common odo issue so it may be of limited value to 8 owners as a whole but it certainly demonstrates the power of the community.


    Thanks again.


    http://forums.bimmerforums.com…p&p=27786635#post27786635

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