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Old 10-27-2011, 08:56 PM
Supercourse Supercourse is offline
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Location: British Columbia, Canada
Join Date: Feb 2008
Posts: 3,890
Mein Auto: 2004 X3 2.5i
Originally Posted by jengstro View Post
That "resistor" / wear indicator. I looked that from old one... I cannot understand how that "inductor?" can measure wear from the plain cover of the motor (on the inside theres no any holes on metal, what could measure rotation or anything?)
My understanding is that some part of the xDrive system uses the resistance detected in operating the wet clutches inside the transfer case to indicate the viscosity or general condition of the gear oil/fluid.

If the pressure required deviates from a certain range, it is concluded that the fluid is degraded.

Nothing to do with the actuator which just has grease in it.

(Measuring electrical conductivity of the fluid would surely be too complex a solution, even for BMW engineers.)
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