Throttle System Operation (GS430 & LS430)
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.
- Remove engine cover. Ensure throttle linkage moves smoothly. Turn ignition on. Depress and release accelerator pedal several times and listen for smooth running sound from throttle control motor. If throttle control motor operates smoothly, go to step 3. If throttle control motor does not operate smoothly or cannot be heard at all, go to next step.
- Check throttle control motor operation. See Throttle Control Motor (GS430, LS430 & SC430) under MOTORS in MOTORS, RELAYS & SOLENOIDS. Replace as necessary. If throttle control motor operation is as specified, check for open or short circuit in wiring between throttle control motor and ECM. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Repair as necessary. If wiring is okay, go to next step.
- Check throttle position sensor operation. See THROTTLE POSITION (TP) SENSOR under SENSORS & SWITCHES. Replace as necessary. If throttle position sensor operation is as specified, check for open or short circuit in wiring between throttle position sensor and ECM. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Repair as necessary. If wiring is okay, go to next step.
- Check accelerator pedal position sensor operation. See ACCELERATOR PEDAL POSITION SENSOR under SENSORS & SWITCHES. Replace as necessary. If accelerator pedal position sensor operation is as specified, check for open or short circuit in wiring between accelerator pedal position sensor and ECM. See appropriate WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, ECM may be defective. Check ECM. See PIN VOLTAGE CHARTS article. Repair as necessary.