Original Poster,

The computer calculates wheel rotations, so if they do not match, then Trifecta light.

- Most of the time the plastic gear is stripped from repeated activation of the xDrive on slippery surfaces such as rain or snow.

- Since you live in California, the plastic gear does not have much of a work-out.

- A rare possibility is your electric motor is kaput. I guess you can apply some battery current to the motor to see if it runs. Anyway, the new actuator should answer the question.

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1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT