GS430, LS430 & SC430
WARNING: This page is about a different car, the 2003 Lexus SC 430, 2003 Lexus LS 430, 2003 Lexus IS 300, 2003 Lexus GS 430, and 2003 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect accelerator pedal position sensor connector. Sensor is mounted above accelerator pedal. See Fig 1. Measure resistance between terminals VCP1 and EP1. Also measure resistance between VCP2 and EP2. If resistance is between 1500-6000 ohms on both circuits, accelerator pedal position sensor is okay. If resistance is not as specified, replace accelerator pedal position sensor.