Originally Posted by feets

I haven't dug into the 170 (SLK) and 193 (Crossfire) electrical systems very deeply. Perhaps I should start.

The M112 engine has both a crank sensor and cam sensor. Be sure you're reading the correct one.
Most tranny speed sensors on MBs read only the turbine input and output speed. Other sensors monitor pressure and then you've got the full solenoid pack. Communication is made through the cable connection with two white O rings that tend to leak. The left front wheel speed sensor is often used as a vehicle speed sensor.
Again, I haven't dug deeply into the 170/193 cars.
Did the speedometer read correctly during dyno runs? It may be looking at the output speed sensor and still function correctly on the dyno.

I'd be interested in spinning up a front wheel via electric motor while the car was on the dyno. It would require either a robust dual roller stand or a serious stand for the car to rest on as it moves around on the dyno.


*EDIT*
Something just came to mind. I don't know if it will help or not, but I can try digging around in the tech library at work and see what I can find on the SLK for a test or other obscure mode. We haven't hooked up to a SLK to try it on them either. If it works, it may give us a road map to use