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Throttle Body

  1. Remove engine cover.
  2. To check throttle control motor operation, turn ignition on. Press accelerator pedal while listening for operating sound at throttle control motor. Ensure that no grinding noise is heard at throttle control motor or throttle body.
  3. If throttle control motor operating sound is heard, go to next step. If throttle control motor operating sound is not heard or grinding noise is heard, throttle control motor, wiring harness or Engine Control Module (ECM) may be defective. ECM is located behind glove box. Go to step  12 for testing of throttle control motor.
  4. To test operation of accelerator pedal position sensor, scan tool or voltmeter may be used. If using scan tool, go to next step. If using voltmeter, go to step  8.
  5. Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Scan tool is used to read throttle valve opening which is displayed as a percentage. Ensure Malfunction Indicator Light (MIL) on instrument panel is not illuminated. If MIL is not illuminated, go to next step. If MIL is illuminated, a Diagnostic Trouble Code (DTC) may be stored in Engine Control Module (ECM). Retrieve DTCs and perform appropriate diagnostic test. See SELF-DIAGNOSTICS - LX470 article.
  6. Rotate accelerator pedal position sensor lever to full throttle while reading throttle valve opening on scan tool which is accessed by THROTTLE POS under CURRENT DATA. Throttle valve opening should be at least 60 percent.
  7. If throttle valve opening is at least 60 percent, go to step  10. If throttle valve opening is not at least 60 percent, problem may exist in accelerator pedal position sensor, wiring circuit or ECM. Go to step  15 for testing of accelerator pedal position sensor.
  8. Access ECM behind glove box. Ensure ignition is turned on. Using voltmeter, check voltage between ECM terminals VPA and E2 with accelerator pedal released and with accelerator pedal fully depressed. See Fig 1.
    Fig 1: Testing Voltage At ECM Terminals VPA & E2
    G98I12482Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  9. Voltage should be 0 volt with accelerator pedal released and 5 volts with accelerator pedal fully depressed. If voltage is within specification, go to next step. If voltage is not within specification, problem may exist in accelerator pedal position sensor, wiring circuit or ECM. Go to step  15 for testing of accelerator pedal position sensor.
  10. Start engine and allow engine to idle. Check operation of Malfunction Indicator Light (MIL) on instrument panel. If MIL is not illuminated, go to next step. If MIL is illuminated, a Diagnostic Trouble Code (DTC) may be stored in Engine Control Module (ECM). Retrieve DTCs and perform appropriate diagnostic test. See SELF-DIAGNOSTICS - LX470 article.
  11. To test operation of air assist system, allow engine to warm to normal operating temperature. Apply parking brake. Place transmission in Neutral. Ensure A/C is off. Note engine idle speed. Engine idle speed should be 650-750 RPM. If all previous steps have been performed, drive vehicle to verify proper operation of throttle body.
  12. To test throttle control motor, disconnect electrical connector at throttle control motor.
  13. Using ohmmeter, check resistance between specified terminals on throttle control motor. See Fig 2. Motor resistance should be .3-100 ohms at 68°F (20°C). If resistance is within specification, reinstall electrical connector. Go to next step. If resistance is not within specification, replace throttle control motor. See THROTTLE CONTROL MOTOR under MOTORS in REMOVAL & INSTALLATION - EXCEPT GX470 article.
  14. To test TP sensor, see DTC P0120, P0122, P0123, P0220, P0222, P0223 OR P2135 under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - LX470 article.
  15. To test accelerator pedal position sensor, see DTC P2120, P2122, P2123, P2125, P2127, P2128 OR P2138 under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - LX470 article.
Fig 2: Inspecting Throttle Control Motor
G00235407Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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