On-Vehicle Inspection

WARNING: This page is about a different car, the 2007 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT LIGHT CONTROL RHEOSTAT
1. Turn the rheostat knob OFF, and check that there is no continuity between terminal 5 and 4 (Rheostat knob turned to fully counterclockwise).
2. Gradually turn the rheostat knob from the dark side to bright side, and check that there is continuity between terminal 5 and 4 (Rheostat knob turned clockwise).
  If operation is not as specified, replace the rheostat.
  
  Fig 1: Identifying Light Control Rheostat Terminals
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002