So, when you replaced your tach sencor, that included the black cylinder on the wheel well, and the gray line that goes down to the crank pulley. How exactly does this system work? I always thought the tach got it's info from the distridutor. Of course our cars don't have one, so what exactly is the sensor above the crank? Does it run off a magnetic field princible? The jet that I work on uses this type of system to measure engine rotations. A sensor sends out a magnetic field. As the engine fan blades pass by the sensor, "breaking" the field, it creates a pulse which then is used to determine fan speed.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member