Xdrive Tester [updated] Info

BMW transfer case fluid contains specific friction modifiers that break down over time. The VTG module tracks fluid wear via an internal algorithm. After draining and refilling the fluid, an xDrive tester must be used to register the oil change, resetting the wear counter. Common BMW xDrive Symptoms Diagnosed with a Tester

A pro-level xDrive tester allows you to command the clutch duty cycle manually. Raise the vehicle on a lift. With the engine running, command the clutch from 0% to 30% to 60% to 90% while watching all four wheels spin. If the front wheels never engage despite a 90% duty cycle command, the transfer case clutch pack is physically worn out. xdrive tester