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Throttle System Operation (GS430 & LS430)

  1. 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.
  2. Check throttle control motor operation. See THROTTLE CONTROL MOTOR (LS430 & GS430)  under 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 WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
  3. Check throttle position sensor operation. See THROTTLE POSITION (TP) SENSOR  under ENGINE 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 WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
  4. Check accelerator pedal position sensor operation. See ACCELERATOR PEDAL POSITION SENSOR  under ENGINE 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 WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, ECM may be defective. Check ECM. See PIN VOLTAGE CHARTS article. Repair as necessary.
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