When the driver's seat & steering column stops moving on the e38 & e39...99% of the time it is the driver's seat module...but it's not the fuse or module itself...it's the wiring harness that goes to the seat module.
This issue on those models usually occurs when the plastic "cover" around the base of the seat breaks away from the seat...since the control module is mounted in this piece, when the driver enters/exits the vehicle, they usually wind up putting weight on this piece, and it ends up breaking the "neck" where the wiring harness attaches.
When the "neck" breaks, it allows the wiring harness to start slipping out...and some of the pins may get bent or it slips out on an angle...which causes erratic functions of the seat & steering column. The fix is to replace the broken plastic seat cover and/or push the wiring harness back into the control module...and find a way to keep it secure.
I've only been on various e53 forums since OCT/NOV 2012...so I'm not sure if the exact same thing occurs on the e53 (the seat design is slightly different)...but the seat control module still controls the steering column, too. So check the WIRING HARNESS to the module.
Below, you can see the wiring harness where it connects to the back of the driver's seat control module...note how the "neck" is broken and allow the harness to slip out:
(e38/e39 plastic seat cover broken away from the seat...which allows control module to get broken)
(neck of seat module is broken as well as lock on the wiring harness)
(broken neck on seat control module)
(driver's seat switch & wiring harness that is intact...not the "white" lock is still in place to secure the wiring harness to the seat control module)
(driver's seat control module (PM-SM) diagram & other items on the P-bus which are under the control of the GM III)
