Taillight Disconnection Warning
WARNING: This page is about a different car, the 2003 Lexus RX 300 and 2002 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.
If any taillight wiring is faulty when the ignition switch is turned to the ON position with the light control switch set at TAIL or HEAD, the light failure sensor detects a voltage difference and is activated to turn on the rear lights warning light in the combination meter to warn the driver. The warning light remains lit until the ignition switch is turned to the OFF position.