DTC P0748: Read Out DTC Memory For Electronic Transmission Control (Etc) Module (N15/3): Notes
WARNING: This page does not describe the selected car, but rather 16 other vehicles, including the 2002 Mercedes-Benz SL500, 2002 Mercedes-Benz S500, 2002 Mercedes-Benz S430, 2002 Mercedes-Benz E55, and 2002 Mercedes-Benz E430. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
This fault will set for 2 reasons; modulating pressure regulating solenoid or switch pressure regulating solenoid.