P1738 - Pressure Control Solenoid "C" Electrical (BMW)

What, and where, is the Pressure Control Solenoid "C" on a '98 7 Series.
This is my brother-in-law's car. He's reporting that the car does not shift
properly -- I've not ridden in the car and I cannot describe the physical symptoms -- and he says it shakes. The Check light came on, and he pulled codes. He reset the codes, drove some more and the symptoms persisted and the Check ultimately came back on. Pulling codes again gave this code as a repeat -- it appeared on both lists of codes.
Is this electrical part one that lives deep inside the transmission, or does it reside on the outside where we can service it ourselves?
I'm searching Google as you read this, but so far I've only found reference to the OBD II code list, I'm looking for a repair strategy.
Thanks. Jeff
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realoem.com shows three solenoids, looks like they're on the control assembly in the pan - part of which looks dry. Look for where the wiring harness goes into the tranny.
FloydR
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