The only way to properly test the cranksensor is to break out the signal and view it on a scope. I don't have the pattern saved on this computer so I have grabbed a small picture from my article on AC:
http://www.continentalimports.com/ser_ic60046.html
I have blown it up here and the shape is discernable. This was taken from a 1991 300e at the sensor to controller connection. We have a special tool to break it out but for years we used a device we constructed from the connetor on a old sensor and te connector from a controler. The problem is it is a coaxial signal wire and it can't be backprobed very easily.
The coil is actually a more statistically probable posibility.