Counter Gear Speed Sensor
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2002 Toyota RAV4, 2002 Toyota Highlander, 2002 Toyota Camry, 2002 Lexus RX 300, and 2001 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.
Counter gear speed sensor detects rotation of counter drive 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 Figure.