CVT CONTROL SYSTEM : Primary Speed Sensor

WARNING: This page is about a different car, the 2011 Nissan Juke. However, it is still accessible from the selected car via links, so may be relevant.

The primary speed sensor is installed to side cover of transaxle.
The primary speed sensor detects primary pulley speed.
The primary speed sensor generates the ON-OFF pulse (short waveform) in proportion to the rotating body speed which is "The higher the rotating body speed is, the faster the change cycle is". The TCM judges the rotating speed from the changing cycle of this pulse signal.

Fig 1: Primary Speed Sensor Functional Diagram With Voltage Output Waveform
Courtesy of NISSAN MOTOR CO., U.S.A.