a diagram I have shows that the camshaft position sensor contains a P-N-P transistor. Output signal for the sensor is at a constant 12 volts until the magnet passes the sensor and the induced voltage acting on the transistor drops the signal voltage to 0 for a brief time. This tells the controller that the number one cylinder is at TDC and the contoller uses this with other signal s from other sensors to make engine management decisions.