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Thread: 98 540i CAN failure?

  1. #1
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    98 540i CAN failure?

    My 540 is getting on my last nerve at this point and if I cant figure out what is going on it may have to move on to a new owner without ever really being enjoyed
    So I come to you with as much information as I can provide and fair warning this post is going to be quite long.

    The previous owner was a mechanic who had somehow managed to make an ignition coil blast the DME and TCU, and the car was running on 4 of 8 cylinders when I bought it. I replaced the computer and had it coded by RPM Motorsport and car has never had an engine related issue since. With that said however, I believe that the initial shock has destroyed something in the car that is not allowing the transmission to correctly shift.

    So this has lead to one major issue when driving. My transmission will shift extremely slow like it does not know where it is, and I have tried just about everything I can to try and resolve it, and I have found nothing close to my symptoms on any forum.
    What it does is this:
    No hesitation or bump from P->R/D
    Reverse is strong with zero slipping, can spin tires in reverse
    Drive has slow shifts between each gear and the kick down is abhorrently bad.
    1->2 500RPM then grabs 2
    2->3 2k RPM then grabs 3
    3->4 2.5-4k RPM then grabs 4
    4->5 bangs off redline unless I let off gas, probably about 4-5 seconds until 5 is grabbed.
    What I have noticed is that each gear is progressively slower than the last.

    (Mechanical Portion)

    This is a used but known working transmission, and I drove the donor car quite hard before agreeing to purchase the transmission, and the drive was perfect, shifted perfect, and the downshifts were great as well. Launched it and everything and not one hiccup. The trans computer was taken from the donor car as well, sent off to RPM Motorsport to be programmed to my VIN, and the used transmission was flushed out and both the tc fluid and the trans fluid was changed, the valve body was inspected with no visible cracks or problems. Used transmission is showing the exact same symptoms as the one that came with the car, so that did not fix it.
    (the mechanical aspect of the transmission is now perfect, no bangs like the old transmission did, and everything is soft but still the same.)

    (Electrical Portion)

    In my last post someone recommended I look at the signals going to the transmission because the transmission is shifting late, and feels like it is slipping. Using INPA I was watching live data through the EGS module, and it was showing normal solenoid action in the either the analog or digital portion, as it has been a week or so since I have worked on this I forget exactly what, I apologize. But you can watch each solenoid engage and then disengage as the transmission moves through the gears. What I have noticed is that my "slow shift" is the exact same position as neutral would be. So from the 2-3 shift for example, I have about a 2k RPM gap before the next gear would engage, and the computer basically shows 2 as engaged, when 2 disengages, neutral sits for about 2k RPM, and then 3 engages. When I shift from park to reverse/drive there is no longer bump or hesitation than my 2014 accord. Only problems are when driving.

    I looked into the ABS light because I have read that the front right passenger wheel sends a signal to the ABS/EGS as to what the car is doing and when to shift. I have had a constant ABS light as well as a DSC light on. I had replaced both the brake sensors and the speed sensors using OEM BMW sensors when I bought the car because I would rather not compromise ABS with aftermarket parts. The light (when reset) would go off for about 20 feet and come back on. DSC never turns off. Upon reading the massive post about diagnosing the problem, I found that since my car is a 98, the ABS module is behind my glove box, and I pulled it and used a multimeter as described in that post to test the wiring and sensors, all 4 came back with fine results and were working. In INPA, the ABS module threw codes for both passenger wheels and the steering angle sensor in the steering column. I decided to swap the sensors from one side to the other and see if it would follow them. Using live data, the module can now see all 4 wheels and they all read correctly weirdly enough the swap fixed it not seeing sensors. When I reset the ABS codes, the steering wheel sensor instantly comes back, and the ABS light goes out, but the DSC stays on, if I do not look at live data and drive the car, the ABS light will stay off. If I use INPA to monitor all 4 wheels, when they reach 17-19.5/20 INPA will throw the NO RESPONSE FROM CONTROL UNIT error and then the ABS light will illuminate once more until reset. Also to just remove it from the equation, I picked up a warrantied known working ABS module from ebay for $30 and programmed it to my VIN using NCS Expert and this had no change on the DSC light or how it acted when being read through INPA.

    Looking into the steering angle sensor through INPA shows that the sensor is in fact working, in the steering angle itself, it shows voltages, and through the ABS itself you can see the angle of the sensor and it is correct. When looking at the CAN bus readings through the steering sensor, there is no initialization for the unit. Would this be causing the DSC light/ ABS light? I will have screenshots of the information from INPA down below. The steering angle sensor calibration using Tool 32 does nothing.

    Some friends have said it may be the voltage regulator.

    TL;DR:
    Car electronics got a hefty dose of voltage before purchase.
    Transmission isnt shifting correctly, known good transmission.
    Replaced DME, EGS, ABS, and EWS.
    New battery and new MAF.
    No Vacuum leaks.
    Any other Ideas before I look into selling the car or manual swapping it? Are there any other modules I am forgetting or any sensors that may be just out of adjustment?

    I am running out of Ideas and I do not have shop money.

    On a side note, while doing all of this testing I found out that my saftey latch is in fact not safe, and am now in need of a new hood since I did not have it all the way closed while reading through the pacman port. Any one have a cheap hood?

    All the screenshots of INPA I have: https://imgur.com/a/Dg1kMid

    No, I was not speeding, my driveway is quite steep and I forgot it was not latched while going up

  2. #2
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    Bump. Anyone?

  3. #3
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    So, you definitely have a steering angle sensor (SAS) problem, and it is the direct cause of the ABS/DSC/Brakes (trifecta) errors and lights.

    INPA error 97 from DSC3 indicates the SAS is not adjusted or calibrated. When you used Tool32 to calibrate it, did you select the right module type (group file DSC3.prg) ?

    If so, then maybe your SAS is defective. Try to clean it then re-install it, and recalibrate. There are few utub videos on how to get to it.
    Quote Originally Posted by PanzerShrekd View Post
    .....
    Looking into the steering angle sensor through INPA shows that the sensor is in fact working, in the steering angle itself, it shows voltages, and through the ABS itself you can see the angle of the sensor and it is correct. When looking at the CAN bus readings through the steering sensor, there is no initialization for the unit. Would this be causing the DSC light/ ABS light? I will have screenshots of the information from INPA down below. The steering angle sensor calibration using Tool 32 does nothing.
    ...
    Last edited by Chedley; 08-06-2020 at 08:11 PM.

  4. #4
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    Quote Originally Posted by Chedley View Post
    So, you definitely have a steering angle sensor (SAS) problem, and it is the direct cause of the ABS/DSC/Brakes (trifecta) errors and lights.

    INPA error 97 from DSC3 indicates the SAS is not adjusted or calibrated. When you used Tool32 to calibrate it, did you select the right module type (group file DSC3.prg) ?

    If so, then maybe your SAS is defective. Try to clean it then re-install it, and recalibrate. There are few utub videos on how to get to it.
    Come to think of it I think I was using DSC5.prg so I will give 3 a try and report back.

  5. #5
    Join Date
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    1997 BMW 540i 6 speed
    It's not a sport if it has an auto trans. All early sports were delivered with the 6-speed manual.
    Last edited by edjack; 08-07-2020 at 02:47 AM.


    Ed in San Jose '97 540i 6 speed aspensilber over aubergine leather. Build date 3/97. Golden Gate Chapter BMW CCA Nr 62319.

  6. #6
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    Just coming back to this, ran the DSC 3 test and It did nothing different. Any other ideas?

  7. #7
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    Defective SAS (steering angle sensor).
    Try to check it and clean it, and most likely, replace it.

  8. #8
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    Quote Originally Posted by Chedley View Post
    Defective SAS (steering angle sensor).
    Try to check it and clean it, and most likely, replace it.
    Dumb question but do you think that would have anything to do with the transmission problem? Or would it be a voltage regulator or bad ground or something?

  9. #9
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    My SAS is throwing code 9. No communication from the ASC module, while the module itself is saying it has no communication with the SAS, does anyone know what pins I would need to check, and if so, what voltages, OHMS I should be looking for? Thanks

  10. #10
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    Quote Originally Posted by PanzerShrekd View Post
    Dumb question but do you think that would have anything to do with the transmission problem? Or would it be a voltage regulator or bad ground or something?
    I do not think the SAS -which seems to be defective- would have anything to do with the transmission problem. Although the electric/electronics of this car are so complex and integrated, that it would not surprise me.
    When you -or the previous owner mechanic - did replace ecu's, did you recode or update the tranny EGS module, ? and did you reset its adaptations ?? I assume you made sure the battery/alternator are fully charged and good, and the tranny fluid and filter are clean and full (basic transmission service)...???
    Last edited by Chedley; 09-02-2020 at 12:32 AM.

  11. #11
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    Quote Originally Posted by Chedley View Post
    I do not think the SAS -which seems to be defective- would have anything to do with the transmission problem. Although the electric/electronics of this car are so complex and integrated, that it would not surprise me.
    When you -or the previous owner mechanic - did replace ecu's, did you recode or update the tranny EGS module, ? and did you reset its adaptations ?? I assume you made sure the battery/alternator are fully charged and good, and the tranny fluid and filter are clean and full (basic transmission service)...???
    Yes the EGS was sent to RPM Motorsport and coded to the Vin, and it was a good used working unit. Transmission was serviced when it was swapped into my car about 50 miles ago, I just wanted to make sure there was no mechanical worry. All adaptations were reset. Battery is new, I have pulsing in lights that are in sync with engine RPM's so I have a new voltage regulator in the mail as we speak.

    Other than the EGS, Trans, and ABS I cant really think of anything else that would cause the late shifting.

  12. #12
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    Other than coding to VIN, Did they update or upgrade the firmware version of the EGS -and other transplanted modules- to the latest released version (per daten files) ? You can check it out if you have INPA and associated diagnostic software (Winkfp) installed and running.
    Software versions mismatch can explain or cause some tranny hickups...!!
    Last edited by Chedley; 09-04-2020 at 01:40 AM.

  13. #13
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    Quote Originally Posted by Chedley View Post
    Other than coding to VIN, Did they update or upgrade the firmware version of the EGS -and other transplanted modules- to the latest released version (per daten files) ? You can check it out if you have INPA and associated diagnostic software (Winkfp) installed and running.
    Software versions mismatch can explain or cause some tranny hickups...!!
    Yeah when they do the reprogram they all get updated. ECU and EGS were both reprogrammed by them. The car was doing the late shifts since before I owned it, and after a new transmission/ EGS, it is still doing it.

  14. #14
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    Quote Originally Posted by PanzerShrekd View Post
    Yeah when they do the reprogram they all get updated. ECU and EGS were both reprogrammed by them. The car was doing the late shifts since before I owned it, and after a new transmission/ EGS, it is still doing it.
    This is just speaking from personal experience, I don't consider myself an expert. On my manual e39, when my abs module was dying and i had the trifecta lights, I would occasionally get ENGINE FAILSAFE PROG errors on my dash. In my manual, this seemed to not do anything so I just ignored it.

    On my friends auto 740, they also had the trifecta lights and would get the engine failsafe prog error, however this seemed to affect their car in the same way you are describing, late and slow shifts. The transmissions in this era of car seem to be really picky about electrical issues, so if I were you I'd attack your trifecta issue before spending more time on the transmission.

    Just my 2 cents, unfortunately my friends 740 got hit while parked by a drunk driver going like 80 in a 20 zone, so we never fixed it.

  15. #15
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    Quote Originally Posted by Deadwake View Post
    This is just speaking from personal experience, I don't consider myself an expert. On my manual e39, when my abs module was dying and i had the trifecta lights, I would occasionally get ENGINE FAILSAFE PROG errors on my dash. In my manual, this seemed to not do anything so I just ignored it.

    On my friends auto 740, they also had the trifecta lights and would get the engine failsafe prog error, however this seemed to affect their car in the same way you are describing, late and slow shifts. The transmissions in this era of car seem to be really picky about electrical issues, so if I were you I'd attack your trifecta issue before spending more time on the transmission.

    Just my 2 cents, unfortunately my friends 740 got hit while parked by a drunk driver going like 80 in a 20 zone, so we never fixed it.
    Do you by chance know what was causing the lights? Codes?

  16. #16
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    Quote Originally Posted by PanzerShrekd View Post
    Do you by chance know what was causing the lights? Codes?
    Unfortunately we didn't have the 20 pin connector to read the ABS module.

  17. #17
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    Quote Originally Posted by Deadwake View Post
    Unfortunately we didn't have the 20 pin connector to read the ABS module.
    all good, thank you

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