SFI SYSTEM DETAILS CRANKSHAFT POSITION SENSOR
CONSTRUCTION
The target has 60 (58+2) pairs of magnetic poles distributed around its circumference, with 2 absent pairs of magnetic poles indicating top dead center of piston 1.
The high/low transition after the 2 absent pairs of magnetic poles indicates that piston 1 is at top dead center (TDC).
As the north and south poles of the target pass the crank position sensor, the output voltage changes between low and high.
A south pole generates a high signal at the output.
The frequency of the square signals produced as the poles pass the target represents the engine speed.