6Hp26 harsh 2-1 downshift - possible solution (at least one of them)
 

My X was driving really good, and about 2 weeks ago it started this 2-1 hard downshift/upshift but only with stone cold engine & transmission.

I knew I had the correct ATF level. The tranny was serviced not too long ago with the correct ZF fluid etc.

There are numerous threads and on-line resources tackling this issue and the "possible" causes are from failed flex disc (guibo) to clogged solenoids, need of new mechatronic unit, low ATF level, etc.

There is also mention of low battery level. And in my case I think this is what it all started, but this is not everything.

You could perform the 2-1 tip in procedure (key in pos II, gas pedal depressed all the way for 30 sec) which is actually a way to reset adaption values if one doesn't have the software (INPA, GT1, etc), but it might only last for 1 or 2 weeks to only return.
In my case, I reset adaption values, but the hard 2-1 shift was still there for the first try, then it faded away. The X was again driving OK, but not quite right (not sure how to explain, to me it seemed the shifts were a bit off from what they usually were).

So, yesterday I decided to see if I have the latest software applied to the tranny, which apparently fixes the 2-1 hard shift issue.

When doing this procedure, you have to bear in mind that the facelift X5 with the 6Hp26 transmission is a bit different from the previous 5 speed tranny. It does not have the "regular" transmission module the famous EGS. So DO NOT SELECT THIS OPTION, you might brick the tranny.
The 6Hp26 has the module incorporated in the mechatronics unit and is called GKE. Select this one when upgrading/re-flashing the module.

Also pay attention to the 2 EGS programmed number & basic number (see below the SIB - they are different for the 4.4 & 4.8) - I know I said EGS, but this is how Progman will ask for it, even prior you have selected GKE. Once you go through the motions explained in the below SIB, you will notice that the computer might be "stuck" as in timed out. It might last 20 minutes or so. Just be patient.

In my case, after I did what is outlined in the below SIB, the X performed exceptionally well on the test drive.

So here is my conclusion: These modules are finicky, and we all know this, testament the "Trans-Failsafe Program" of the tranny when the battery is low, or numerous glitches related to low battery. The thing does not stop here, I believe. You can re-charge the battery, or install a brand new battery, or install a new alternator. What I think happened in my case is the low battery triggered the hard 2-1 shift which is probably at the brink of the "trans-failsafe" program. And I think, once this happens, the GKE module is compromised (Remember I reset the adaptation values, but at first it didn't catch, then shifting wasn't quite right). In my case the solution was to re-flash the GKE - and yes, I had the latest software confirmed by the program.

Also, if you attempt this, make sure you have a good charger (BMW recommends a 40Amp charger), but I got by with a 12 Amp charger, which I think is the bare minimum.

below is the SIB 24 01 06 (again, when using Progman select GKE and NOT EGS - you are warned):

Automatic Transmission

August 2007
Technical Service

This Service Information bulletin supersedes S.I. B24 01 06 dated November 2006.
[NEW] designates changes to this revision
SUBJECT
E53 X5 N62 - Harsh 2-1 Downshift

MODEL
X5 4.4i/4.8is with 6HP26 from 10/03 up to 08/05

SITUATION
Customer may complain of the following:

- An excessively harsh 2-1 downshift when decelerating to a stop, or
- Transmission "bangs" into gear when accelerating from a full stop, or from a "rolling stop" (vehicle did not come to a complete stop).
CAUSE
EGS software.

CORRECTION
On a customer complaint basis only, reprogram transmission control module (EGS/GKE) with SSS loaded with on-line update Progman V20.01.00, or higher.

After programming is successfully completed, the following EGS part numbers should be displayed in the module identification page:
[NEW] X5 4.4i
EGS programmed number 7 564 917,
EGS basic number 7 557 063.

[NEW] X5 4.8is
EGS programmed number 7 564 921,
EGS basic number 7 557 063

PROCEDURE
Important:
Prior to EGS module reprogramming, transmission temperature must remain below 50 deg C and transmission shifter be must be placed in a P position.

To reprogram the EGS transmission control module:
1. Connect the vehicle to a BMW approved battery charger.
2. Connect SSS loaded with CIP 20.01.00 (on-line update), or higher.
3. Select: X line of vehicles, and then E53.
4. Question: Were any control modules replaced? is displayed. Select: No.
5. From the right-hand column select: EGS, then Programming, then Update software.
6. After few minutes, the measure plan is going to be displayed. Select Accept, and then Start.
7. Follow screen instructions.
WARRANTY INFORMATION
Covered under the terms of the BMW New Vehicle Limited Warranty.

So this can be done with the INPA, GT1 software?

If you have INPA/GT1 you should also have SSS Progman which is the programming software.
And I believe GT1 will let you do that as well - last evening when I was doing it with my friend Fmugur who is a member of this board, I believe we went through the GT1 once, but I cannot remember correctly what stopped us. He might chime in later.
I know he tried with a different software at first, but we couldn't establish communication with the tranny. This is why I believe once the battery power is below a certain threshold, it might corrupt the software in the Mechatronics. Even the GT1 & INPA didn't recognize the tranny module anymore. It looked like bricked. Once the software was reflashed, I could connect with GT1 & INPA.

These are my observations and might not be similar to yours, but in my case I could at least check with decent software. An over the counter scanner would not be helpful at all in this situation.

Good to know.

Sorry to dig up an older thread, but to be clear your saying the egs program number for the newer update to fix the 2-1 down shift is 7564917? Because when I go into inpa and check my transmission module assy # is says 7564917. So this would indicate my trans has already been updated at some point? Thanks

The mentioned number is the code of your specific GKE module. You enter that number if it's a 4.4, followed by the basic number when prompted (7557063).
Once the re flash is successful, the software will prompt with the software number that replaces the old one, and if it was successful or not. In my case, it was the same number (can't recall what the software iteration was).

I have a question on the EGS Programmed number. I just went through program and found I had: 7 564 917 I let SSS Progman update date it via new measures and it installed the same 7 564 917 again.

Now here is my question: My X is a 4.8is. Per the TIS that comes back to the 4.4 ?

[NEW] X5 4.4i
EGS programmed number 7 564 917,

[NEW] X5 4.8is
EGS programmed number 7 564 921,


My production date is Jan 2005 (26.01.2005) and my engine has an aircooled alternator so maybe the very early 4.8's had something not fully 4.8?

Anyone done this update on a 4.8is yet? Did you find 7 564 921 or 7 564 917?

thanks much !
J

If it's a 4.8, then you should use the numbers for your specific vehicle. The 4.4 has different numbers. these numbers I believe have to do how the transmission will perform - the 4.8 has a different engine, and probably will have different shift rpm values, etc. And you should use both numbers:
EGS programmed number 7 564 921,
EGS basic number 7 557 063
Not sure how the TIS should come back to you with the 4.4 numbers? Progman handles the coding & re-flashing. The TIS is the skinny version of BMW's DIY. And the updated technical bulletin service was released years after the TIS.

Hi Doru
thanks for the reply
Understood and agreed on how progman sss handles the versions and it appeared to smoothly however it was indeed progrman sss that gave me the 4.4 number of 7 564 917 when I let it auto select as recommended.

There does look to be a manual way to enter in part number but that scares me on frying the trans computer.

Anyone know way I can tell the difference between a 4.4 and a 4.8is trans (in an e53) by looking at the case or anything?

In my case, I didn't let the software autoselect, but I also have the 4.4
If you have concerns, I would pay a visit to the dealership & try to ask one of their master techs about these numbers. I am pretty sure you need to use the 4.8 set posted in that SIB, you might not have the latest software, and prolly that's why it goes to the 4.4 numbers. But I would check with the dealership nonetheless, and then if you don't mind, post here the findings, so others can benefit as well.