Counter Gear Speed Sensor (NC)
WARNING: This page is about a different car, the 2003 Toyota RAV4, 2002 Toyota RAV4, 2002 Toyota Highlander, 2001 Toyota RAV4, and 2001 Toyota Highlander. However, it is still accessible from the selected car via links, so may be relevant.
Counter gear speed sensor detects rotation of counter gear. By comparing counter gear speed sensor signal and input turbine speed sensor signal, ECM detects shift timing of gears and controls engine torque and hydraulic pressure in response to various conditions, resulting in smooth transaxle shifting. See Fig 1.