On Board Diagnostic (OBD), Function: Notes
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2003 Volkswagen EuroVan, 2002 Volkswagen EuroVan, 2001 Volkswagen EuroVan, 2000 Volkswagen EuroVan, and 1999 Volkswagen EuroVan. However, it is still accessible from the selected car via links, so may be relevant.
The automatic transmission is controlled electro-hydraulically.
The term "On Board Diagnostic" is specifically for the electronic/electric control.
The automatic control module -J217- receives information from components that effect selection of gears and passes the information on to solenoid valves that control the valves in the valve body.
The control module is equipped with a Diagnostic Trouble Code (DTC) memory so that in the event of an electronic/electrical component failure or on open circuit the malfunction can be determined quickly. malfunctions are recognized by electrical signals and stored in the DTC memory.