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Thread: E34 540: No communication with AGS

  1. #1
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    Default E34 540: No communication with AGS

    I am the proud owner of a '94 540 (E34) with "I think" all possible options installed from the factory.

    Last year the gearbox broke down, and I had the local mechanic change it to a another used gearbox.. then the trouble started.

    First indication was the passenger-side mirror - it has the option to turn down (to watch the backtire) whenever the car is put in reverse.. After the gearbox-change - it points up instead!..

    The car also started having trouble getting in motion from standing still in "D".. and now its so bad I have to put the gaspedal all the way to the floor to get i moving.
    As soon as the gearbox "catches" first gear, everything works just fine.. Also when the gearbox is in "N" it reverses slighty.
    I was pretty sure the new gearbox was broken - so we have changed it to another one.. still same problem.
    I have also switched the AGS-box.. still same problem.

    When I install an AGS from a 740 the car goes into transprogram (ofcourse), but it runs just fine in third gear, and no reverse in N..
    So by now Im pretty sure its something going on in the controlmodule (AGS) or some other external signal http://www.e38.org/electran1.pdf (page 10)

    Anyway - I needed to get inside the diagnotics of it to see what is going on.
    So I bought this kit: http://www.uobd2.net/wholesale/bmw-icom-a2-b-c-with-wifi.html

    It works fine (I think) - I am able to start Reingold and get in contact with the car.. But Im only able to communicate with two modules -DME and IHK(climate control).. and nothing else.. And I know there is a lot more of the modules I should be able to communicate with.
    So maybe the fault is somewhere on the communication-bus - according to http://www.e38.org/e34/e34_94_etm.pdf ,the DME and AGS should be right beside eachother on the com-bus.. (And I have tried with several AGS-modules)

    I could really need some good pointers on where to go from here - what am I missing ?

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    Last edited by schwartz; 08-26-2015 at 02:42 PM.
    Jørgen Schwartz
    1994 BMW M540 Individual

  2. #2
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    You need to establish a few things:
    1. Is the ATF level is correct and is the shift cable is adjusted correctly?
    2. If you disconnect the AGS, is reverse and 4th gear ok and no issue with reverse in N as per the 740i AGS?
    3. What happens when you put the lever in 4,3,2?
    4. That the Rheingold kit is designed for the E34. The system is ADS, not OBD

    I would be very concerned that the gearbox is engaging reverse when it should not be. Apart from the fact that it may feel like you are driving with the handbrake on, there is no way of knowing if it is engaging reverse at the same time as forward gears. But if it is doing that, it will self destruct in a very short time.
    Oct '00 E46 330i. Feb '92 525i (departed)

  3. #3
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    Thanks

    1. ATF is ok - and I would think the cable is adjusted correctly because it works without AGS
    2. yes.. - so not really sure why I use the 740i AGS
    3. same as in D... but when I move the lever all the way to 2 and back to 3 - the gearbox works as it should for 5-10 seconds.
    4. Since Im getting communication to work with two different modules.. I guess it has to be the right version I am using? - I am using the round connector in the engine compartment.
    Jørgen Schwartz
    1994 BMW M540 Individual

  4. #4
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    Quote Originally Posted by schwartz View Post
    Thanks

    1. ATF is ok - and I would think the cable is adjusted correctly because it works without AGS
    2. yes.. - so not really sure why I use the 740i AGS
    3. same as in D... but when I move the lever all the way to 2 and back to 3 - the gearbox works as it should for 5-10 seconds.
    4. Since Im getting communication to work with two different modules.. I guess it has to be the right version I am using? - I am using the round connector in the engine compartment.
    Just to be 100% sure, I'd make sure the cable is adjusted correctly. Also that the lever on the side of the gearbox is actually moving and taking the spindle with it :-) Can you get 4,3,2 and reverse OK with the AGS disconnected and do they work fine?

    I know nothing about the kit you have but it appears to be OBD2 and the E34 is not. You should be able to communicate with a lot more than those two modules. You are using the right connector - it is the only one on the E34 :-)
    Oct '00 E46 330i. Feb '92 525i (departed)

  5. #5
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    I will check again without AGS, as soon as I get home from work.. But Im pretty sure they all work - its only when the AGS is able to communicate with the car it all goes horrible wrong .
    Could you point me in the direction of a kit you know for sure will work ?
    Jørgen Schwartz
    1994 BMW M540 Individual

  6. #6
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    I have now checked without any AGS, and D,4,3,2 are all ok, reverse is ok and N and P is ok.. So it only goes wrong when connecting a working AGS.

    I also noticed the passengermirror still goes upwards in reverse.. when no AGS is connected.. So something else is causing it.
    Another thing I have noticed the last year is that I had a a function called comfort-wash of the windshield, as well as the IR-key doorunlocking has stopped working... as far as I know the washer and mirror (and maybe the IR og door unlock) is controlled by the ZKE-box..
    Could a faulty ZKE be messing up the AGS-box? or is this to far out?

    Regarding the communication, I think your right.. I read there is K-line and L-line protocol (or something).. and apparently I need an ADS:OBD interface to read both.. I have now ordered this: http://www.interfaces4beemers.net/adsobd.html
    apparantly its the best one out there, and it should work fine with Rheingold.
    Jørgen Schwartz
    1994 BMW M540 Individual

  7. #7
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    When you disconnect the AGS or you get trans program, all power to the solenoids and pressure regulator is switched off. The ATF pressure is not regulated but runs at maximum. The issue may seem to be with the AGS but I think it may be as simple as a blocked filter or gummed up valve body. When you get the new kit, a diagnostic check will help you decide which is the cause.

    As I understand it, you only get trans program when you replace the AGS with one from a 740i. That suggests there are no major problems with the AGS itself or the solenoids, switch matrix etc. There are two speed sensors inside the gearbox and they monitor the input and output speed and the AGS compares them. If it finds that the difference is outside parameters e.g. due to slip, you will normally get trans program and the AGS will store a speed sensor fault code. Don't you get trans program when you engage D and there is a long delay before it engages?
    Oct '00 E46 330i. Feb '92 525i (departed)

  8. #8
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    The problem is that I do NOT get transerror when inserting the correct AGS.. but the gearbox does funny stuff (read first post).. The stuff regarding the E740 AGS and no AGS, was just to isolate if the problems was related to the gearbox or AGS-module.
    The gearbox has been swapped (twice) and the AGS has been swapped - so I know they work.

    I spend last night looking through wiring-diagrams and found out that I might need to focus some more on the passenger-mirror going upwards instead of dipping when the gearselector is in reverse.. As far as I can tell the cables/connectors for that function runs in the same wiring-harness as the gearbox-control cables.. maybe the mechanic damaged the harness the first time they changed the gearbox - resulting in faulty signals being send from the AGS.. this would explain a lot - also why Im not getting Transerror.

    Does any of you guys know if its possible to get to the harness, and maybe change it, without having to take the transmission out of the car ?
    Jørgen Schwartz
    1994 BMW M540 Individual

  9. #9
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    You only get the passenger mirror self adjusting when you engage reverse if you have memory seats. The memory seat/mirror module controls the movement of the mirror. It is also linked to the alarm system so may be the reason you are having trouble with that too. AFIK, the only input is from the range switch so it should be fairly easy to check. Do your reversing lights work OK?

    You don't need to remove the transmission to get to the harness - it just unplugs :-) So it should be an easy job to check the wiring for breaks/continuity. (I missed the part where you said you had already changed the gearbox and still had the same problem) What SHOULD happen if there is a short/break is that the AGS should throw trans program as soon as you switch on. But I have heard of a case where the wiring was a complete mess and this didn't happen. So I think you may well be onto something. Hope you will keep us informed of progress
    Oct '00 E46 330i. Feb '92 525i (departed)

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