Vehicle Speed Sensor
WARNING: This page is about a different car, the 2003 Lexus GX 470. However, it is still accessible from the selected car via links, so may be relevant.
If a Vehicle Speed Sensor (VSS) circuit fault is present, a Diagnostic Trouble Code (DTC) should set. Retrieve DTCs and perform appropriate diagnostic test. See SELF-DIAGNOSTICS - GX470 article.