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Thread: Transmission limp mode - How to ensure replacement is really required?

  1. #1
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    Question Transmission limp mode - How to ensure replacement is really required?

    Hi,

    Two weeks ago I bought a 1999 740i E38. Less than 200 km driving slowly with it the message "trans fail prog" appeared and the car has been stock in high gear, likely 4th.

    The transmission is a rebuilt unit and has 9000 miles. Dealer told me that transmission needs replacement since the limp mode is staying despite reset and that they found metal particules in the oil.

    The thing is that the transmission was really smooth, all the time.

    What should I do to ensure that it really requires replacement?

    Many thanks for feedback.

  2. #2
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    My over priced mechanic was laughing when he told me about a 07 Nissan whos tranny dont work. I just said, " They probably put the wrong kind of tranny oil."

    Certain cars require different types oil. Not the ones you find at your local auto supply store. So if I were you I would try changing the tranny filter and oil. DIY



    Sent from my SM-N900T using Tapatalk

  3. #3
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    Perform diagnostics as a first port of call - there are many electrical problems that can cause TRANS FAIL-SAFE PROG, you might be lucky enough to have something simple. Let us know what the codes are and we will be able to advise you further. Without diagnostics we would just be guessing!
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  4. #4
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    Perform a trans oil filter change them check your harness for shorts. My E39 transmission went into limp mode over a wiring short issue

  5. #5
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    That is what I figured, there must be more info available from the computer about what is triggering the TRANS FAIL SAFE PROG. The dealer did hook the scanner but the only thing they mentioned that there are 59 msg about the transmission (I only saw 1 myself) and it need new transmission.

    I guess I will have to invest in a scanner or something to know more.

    - - - Updated - - -

    Harness, that won't be easy to check. Some switches also maybe?

  6. #6
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    How's your battery?

  7. #7
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    Quote Originally Posted by Mayorchuck View Post
    How's your battery?
    this

  8. #8
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    It had been discharged the day before (forgot driving light all night) but before driving and having the issue with the transmission, I fully recharged it. One pole was loose and I did fix that too. So the battery has no problem to start the car.

    - - - Updated - - -

    The transmission was really smooth and I really drove it carefully. But then I only had it for about 120 miles.

    - - - Updated - - -

    Any info on how to check for harness shorts? Where to look first?

    Quote Originally Posted by XSTARSCREAMX View Post
    Perform a trans oil filter change them check your harness for shorts. My E39 transmission went into limp mode over a wiring short issue
    Last edited by jfparent; 09-15-2017 at 09:52 PM.

  9. #9
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    My personal experience with TFS is having it on three different E38's. It was the battery every time. Not familiar with any harness issues.

  10. #10
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    If it were the battery, wouldn't the dealer found that up? Should I connect a power pack directly on the battery to see if it change anything with the TFS? I could also monitor the battery voltage?

    Quote Originally Posted by Mayorchuck View Post
    My personal experience with TFS is having it on three different E38's. It was the battery every time. Not familiar with any harness issues.
    - - - Updated - - -

    Is the Carly app and OBD2 module a good option? I have an iPad. Thanks.
    Last edited by jfparent; 09-16-2017 at 11:26 PM.

  11. #11
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    For what it's worth, I recently had a trans failsafe problem, not starting, going to fail safe when shifting. It was the shifter position switch.

  12. #12
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    Can you indicate where to access the switch? In the central console near the stick shift?

    Quote Originally Posted by motion View Post
    For what it's worth, I recently had a trans failsafe problem, not starting, going to fail safe when shifting. It was the shifter position switch.

  13. #13
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    I have a '01 Sport with the A5S440Z transmission, the switch is located between the shifter selector cable and the transmission. On a A5S560Z transmission it's located on the passenger side opposite the shifter cable. Timm did a real nice write up on how to check the switch.
    http://www.meeknet.co.uk/e31/timms_b...e_problems.htm

  14. #14
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    Quote Originally Posted by Mayorchuck View Post
    My personal experience with TFS is having it on three different E38's. It was the battery every time. Not familiar with any harness issues.
    I wasn't as lucky. When got the dreaded TFS my tranny had actually failed - bad valve body if I remember correctly. Went ahead with a complete rebuild. That was 4yrs ago.

  15. #15
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    First, I want to thank all for helping me with this issue. I am proceeding in order of potential issue likelihood mixed with ease and cost of verification.

    So, I been testing a few things to day on the car. Here is what I have observed:

    (1) Just by monitoring the battery voltage with the diagnostic test #9, the voltage is at 11.8V which seems to be too low.

    (2) With the TRANS FAIL SAFE PROG (TFSP) msg ON, the car seems to be in 3rd gear and offer some drivability. Slow start but normal and smooth at around 35MPH. I did not try to go at highly speed yet.

    (3) If I do a computer reset (unlock with diagnostic test #19, then reset with #21), the TFSP msg disappear but now the transmission seems to be stock in the 5th gear and its not drivable (I press on gas on flat surface and the car barely move).

    (4) I go in reverse and forward, try to move a few meters until I get the TFSP msg appear again and with it the transmission goes better (as described in (2) above with the 3rd gear available).

    So the question is, with those new details:

    What exactly is happening with that transmission (5th gear only without TFSP and 3rd with TSFP msg)?

    And please let me know if the following could cause me trouble:

    I am planning to:

    (1) Recharge my battery again
    (2) Connect a battery pack (Motomaster Nautilus) directly to the battery (!?!)
    (3) Test transmission (with and without TFSP msg).
    (4) If not helpful, disconnect the battery while keeping the battery pack connected to the car (hoping not to loose the battery registration)
    (5) Have the battery tested and replace if required.
    (6) Test the transmission again.

    Is that OK to connect the battery pack to connections in the trunk instead of under the hood?

    And again, thanks for all you help!

    - - - Updated - - -

    Hi Toomann, what were the symptoms and you transmission? Only the TFSP msg?

    Quote Originally Posted by toomann View Post
    I wasn't as lucky. When got the dreaded TFS my tranny had actually failed - bad valve body if I remember correctly. Went ahead with a complete rebuild. That was 4yrs ago.
    - - - Updated - - -

    Thanks Motion, that is next on my list!

    Quote Originally Posted by motion View Post
    I have a '01 Sport with the A5S440Z transmission, the switch is located between the shifter selector cable and the transmission. On a A5S560Z transmission it's located on the passenger side opposite the shifter cable. Timm did a real nice write up on how to check the switch.
    http://www.meeknet.co.uk/e31/timms_b...e_problems.htm

  16. #16
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    Quote Originally Posted by jfparent View Post
    First, I want to thank all for helping me with this issue. I am proceeding in order of potential issue likelihood mixed with ease and cost of verification.

    So, I been testing a few things to day on the car. Here is what I have observed:

    (1) Just by monitoring the battery voltage with the diagnostic test #9, the voltage is at 11.8V which seems to be too low.

    (2) With the TRANS FAIL SAFE PROG (TFSP) msg ON, the car seems to be in 3rd gear and offer some drivability. Slow start but normal and smooth at around 35MPH. I did not try to go at highly speed yet.

    (3) If I do a computer reset (unlock with diagnostic test #19, then reset with #21), the TFSP msg disappear but now the transmission seems to be stock in the 5th gear and its not drivable (I press on gas on flat surface and the car barely move).

    (4) I go in reverse and forward, try to move a few meters until I get the TFSP msg appear again and with it the transmission goes better (as described in (2) above with the 3rd gear available).

    So the question is, with those new details:

    What exactly is happening with that transmission (5th gear only without TFSP and 3rd with TSFP msg)?

    And please let me know if the following could cause me trouble:

    I am planning to:

    (1) Recharge my battery again
    (2) Connect a battery pack (Motomaster Nautilus) directly to the battery (!?!)
    (3) Test transmission (with and without TFSP msg).
    (4) If not helpful, disconnect the battery while keeping the battery pack connected to the car (hoping not to loose the battery registration)
    (5) Have the battery tested and replace if required.
    (6) Test the transmission again.

    Is that OK to connect the battery pack to connections in the trunk instead of under the hood?

    And again, thanks for all you help!

    - - - Updated - - -

    Hi Toomann, what were the symptoms and you transmission? Only the TFSP msg?



    - - - Updated - - -

    Thanks Motion, that is next on my list!

    When my tranny failed it would start out in I think 3rd gear. The car was difficult to get going forward. Once going it was drivable but not from a dead start. I did still have reverse.

  17. #17
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    That is what TFS does. Default is either 3rd or 4th and that's the only gear that works. You can't diagnose anything further until you have a fully charged battery, as that is the cause of 80+% of TFS.

  18. #18
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    Yes, I understand this but the strange thing is that before the TFS appear (following a reset), I am stock in 5th gear and can't move whatsoever. When TFS appears, then I can move starting slowly but fine.

    Quote Originally Posted by Mayorchuck View Post
    That is what TFS does. Default is either 3rd or 4th and that's the only gear that works. You can't diagnose anything further until you have a fully charged battery, as that is the cause of 80+% of TFS.
    - - - Updated - - -

    I am charging the battery on repair mode (on the charger). I will fully test it and change if bad.

  19. #19
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    My guess is that you are not stuck in 5th gear - you actually have no gear at in 1st - 3rd due to a failed clutch pack, it is only when you get the TFS that the gearbox will drop into 4th gear and you get some drive back again. Diagnostics will give you the 'Output Speed Sensor' fault - the kiss of death for the gearbox.....
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  20. #20
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    Tried with a fully recharged battery (13.7V) and no luck.

    Next step is the diagnostic with a OBD2 bluetooth transmitter and an Android tablet that I am borrowing from a friend this evening. I will buy one in a near future, after I find which one to select (read/clear/program + register battery).

    Quote Originally Posted by Timm View Post
    My guess is that you are not stuck in 5th gear - you actually have no gear at in 1st - 3rd due to a failed clutch pack, it is only when you get the TFS that the gearbox will drop into 4th gear and you get some drive back again. Diagnostics will give you the 'Output Speed Sensor' fault - the kiss of death for the gearbox.....

  21. #21
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    I went through a rough patch with TFS and as Mayorchuck and others mention, a weak/poor battery is often a culprit. Might just want to get a new one to remove that from consideration. I got TFS one time because of a short in a tiny wire coming out of the thermostat (thought the car was overheating) and it was a simple fix.

    One concern I have is in your original post where you mention metal pieces in the tranny and that the fluid may not be OEM/correct. I had a bad transmission shudder for a while that a fluid flush/replace and new filter remedied. Again, this might remove certain things from consideration - and if you have the bottom of the tranny pan off, you may see/find something while in there.
    '01 325Ci Convertible, 5-speed
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  22. #22
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    Quote Originally Posted by jpilk99 View Post
    One concern I have is in your original post where you mention metal pieces in the tranny and that the fluid may not be OEM/correct.
    The oil should be OEM correct since the transmission was installed by a BMW dealer at the time (9000 miles before).

  23. #23
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    Question

    OK, so for the code (just a regular scanner, not a BMW specific) I got only one code, that is P0720, the output shaft sensor circuit. Also, after erasing the code and placing the transmission in the manual mode, I was able to see the gears in the dash. Initially at 1 but car not moving, after maybe 30 sec, it went to 2,3,4,5 automatically (in about 3 sec) and I got the TFS message and some drivability.

    BTW, in reverse, the transmission respond really well, so I don't think there is any slippage with the torque converter.

    Is there any way to test this output shaft sensor?

    Timm mentioned the "kiss of death" for the gearbox in this case and failed clutch pack, could I have more info please?

    Thanks!

  24. #24
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    Unfortunately you have the error message I expected - although the error message says 'sensor' what it is reporting is that there is no signal when expected from the output shaft sensor - and the reason that it is not getting a signal is that the output shaft is not turning (rather than the sensor being faulty). The shaft is not turning because you have a failed clutch pack (clutch pack 'A') which serves 1st to 3rd gears.

    Once the EGS evaluates that the output sensor is not turning it will select 4th gear - the clutch pack that serves 4th and 5th gears does not see anywhere near as much torque as the lower gears and usually survives longer than the 'A' clutch.

    The bottom line is that you have a mechanical failure of the gearbox and you can either replace or repair it....
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  25. #25
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    Thanks Timm, not a good news but at least I know I will not be removing a good transmission.

    Sooo, now I will swap to a manual... between the 740i 5 speeds and 540i 6 speeds (probably the 6 speeds).

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