I suppose you could run the vehicle on jackstands (very carefully....) and read the signal at the connector on the outside of the transmission. That would tell you if there is a signal from the output speed sensor. I think it is a sine wave, so it is either going to be there or not, you aren't going to have an inaccurate reading IMO.

But really, the message you are getting (as I recall it) had to do with a problem with the output speed sensor reading. The computer reads the input speed and the output speed, and compares them. If they are too different, it says there is an implausible reading. It doesn't mean that the sensor is faulty, just that the sensor isn't reporting what the controller expects it to. The most likely cause for that is that the transmission is slipping. And you know already that it is, both from the driving characteristics and from the burnt fluid. So I wouldn't think that the output speed sensor would be a cause, rather an early warning that slipping has started. But you already know that.

There are tests for the solenoids that activate various circuits. But you are only checking electrically. The transmission is a mechanical/hydraulic/electronic system. All the monitoring and faults are reported electronically. But that doesn't imply that the root cause is an electrical fault, as a mechanical or hydraulic problem will show up as an electrical fault (symptom vs cause).

Good luck.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
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