This bulletin applies to 2009 and later Volkswagen Routan vehicles. If a transmission diagnosis points to a low clutch concern, monitor the main pressure (under data display) during reverse. If there is pressure loss in the low clutch, it will show when in reverse because reverse is essentially maximum output pressure.
When monitoring actual vs. specified data (both available under data display), a reading of 10-40 psi lower than actual may indicate a faulty piston seal.
This would work when diagnosing 1st, 3rd and 4th gear concerns.
Low clutch is used only for engine braking during these gears (activates only during coast). During reverse, it is fully engaged and under higher pressure.