When the 6HP26 tranny came out and was installed on various BMW iterations, most of these cars exhibited the 1-2 hard shift issue. BMW tried fixing it with I think 1 or 2 different software which failed. The last version of the software, however fixed this hard shifting issue. I am not sure which the number is or what year it was (sometime between 2007-2009 I believe), but if you have the latest GT1/INPA/Progman SSS, then you should have this version. When I re-flashed the tranny, I know I had the latest, but as I said it "glitched" and went in the 1-2 hard shifting mode, but I omitted to write down the software version.
If the vehicle runs fine, don't touch it. If for whatever reason it starts to exhibit the 1-2 hard shifting pattern, the first step is to re-flash the tranny module. When doing it with the latest GT1/Progman SSS software, when programming, the software will prompt you what software version will be replaced. In my case it was replaced with the same software, so I know I had the latest.
I found
the link with the 6HP26 issues and possible fixes. Tonight I will update with the pdf on how to program the tranny and the numbers you have to use for the different 4.4 and 4.8 transmissions.
04-15-2015, 02:44 PM
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