The transmission in this GL, some ML’s and many other Mercedes vehicles have problems with one of the sensors failing intermittently and causing the transmission to not shift. This plate is located above the Valve Body inside the transmission and houses not just the main transmission speed sensors but also the shift solenoids and the transmission control module itself which is part of what makes this such a difficult repair.
First step is to get the vehicle to act up long enough to determine its an actual internal transmission electrical problem. The next step is to pull the lower part of the transmission out to get access to the old part, and replace it with the new one. Code the new module to match this vehicle and set up the anti-theft so that it will start when its done. Lastly relearning the new transmission module to know how to properly shift your older transmission.
The software side of this repair is the part that makes it so that most shops wont be able to do the work and will probably tell you that it will have to go to the dealer. Luckily our shop is set up to do these kind of tough repairs on most European vehicles including Mercedes, BMW, VW, Mini, Volvo and Saab just to name a few. We also can do programing on most Domestic and Asian vehicles as well.