What leads you to believe that the DSC is not activating?

The DSC is normally always active, with all-wheel-drive (4x4) being the normal operational mode. The DSC will manage the torque to each wheel (via transfer case clutches and ABS modulation) under all conditions.

A failure of the DSC system (as detected by on-board diagnostics) is indicated by warning lights on the dash. Do you have any warning lights?

If the internal (plastic) gear in the transfer case has worn to the point of failure, you will often hear it clicking under the car a couple of seconds after shutting the car down (when the DSC system does a self-alignment, after every drive). The clicking sound is the worm gear on the actuator motor, skipping on the worn teeth of the plastic gear.

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Wayne
2005 BMW X5 3.0d (b 02/05)
2001 BMW F650GS Dakar (b 06/01)