The Mercedes Benz M103 engine is a 6 cyl engine and uses three teeth on the flywheel, each 60 degrees wide, leaving a 60 degree window between them. There is a single inductive/VR sensor of 830 Ohm to sense these teeth, the sensor wire has only one conductor with a shield.
Which is proper to use as ground and which is signal? I'm looking for the correct polarity.
I could just connect the signal and try it out live, but I have a few days until the fuel system is complete so I would like to investigate first if possible.
Notes :
The primary trigger input on the ECU has a 1k pulldown, lm1815pin5=5V
The scope image below shows the signal picked up by the sensor while cranking at about 200 rpm.
The ground of the probe is connected to the shield of the sensor wire.
It is unknown which edge of each "tooth" is at TDC for each cylinder, but one of them is. If I'm not mistaken, the polarity will matter to get the correct edge to occur 60 degrees before TDC.
More on the engine here: http://en.wikipedia.org/wiki/Mercedes-Benz_M103_engine