GS400, LS400 & SC400

Disconnect Throttle Position (TP) sensor connector. Do not confuse TP sensor with accelerator position sensor. Both sensors have 4-pin connectors and are mounted on throttle body. Check wire colors to help identify TP sensor connector. See appropriate wiring diagram in WIRING DIAGRAMS article.
Measure resistance between terminals VC and E2 at TP sensor sensor. See Fig 2. Resistance should be 1250-2350 ohms at 68°F (20°C). If resistance is not 1250-2350 ohms, replace TP sensor.

Fig 1: Identifying Throttle Position (TP) Sensor Terminals (GS300 & SC300)

Fig 2: Testing Throttle Position (TP) Sensor (GS400, LS400 & SC400)