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Home >> Lexus >> 1996 >> SC 400 >> Repair and Diagnosis >> Brakes >> Traction Control >> Traction Control System >> Circuit Tests >> DTC 47 - Sub-Throttle Position Sensor Circuit >> Diagnosis & Repair
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Diagnosis & Repair

  1. Determine if any engine DTCs are present. See appropriate TESTS W/CODES article in ENGINE PERFORMANCE section. Repair as needed. If no engine DTCs exist, go to next step.
  2. Turn ignition on. Remove intake air duct at throttle body. Using voltmeter, backprobe TRAC ECU harness connector T13. Measure voltage on terminal No. 19. Monitor voltage while opening sub-throttle valve to wide open throttle. Voltage should be 1.5 volts or less with throttle fully closed, and 3-4.5 volts with throttle fully open. If voltage is within specification, go to step 7). If voltage is not within specification, go to next step.
  3. Turn ignition off. Check continuity of VSH circuit between TRAC ECU and ECM. Repair as needed. Ensure circuit is not shorted to ground. If circuit is okay, go to next step.
  4. Disconnect ECM harness connectors. Install check connector. Remove air intake duct at throttle body. Turn ignition on. Measure voltage between ground and terminal No. 39 on connector "A". Monitor voltage while opening sub-throttle valve to wide open throttle. Voltage should be 1.5 volts or less with throttle fully closed, and 3-4.5 volts with throttle fully open. If voltage is within specification, replace TRAC ECU. If voltage is not within specification, go to next step.
  5. Measure voltage between terminals No. 12 and 65 on check connector "B". Monitor voltage while opening sub-throttle valve to wide open throttle. Voltage should be .3-.8 volts with throttle fully closed, and 3.2-4.9 volts with throttle fully open. If voltage is within specification, replace ECM. If voltage is not within specification, go to next step.
  6. Turn ignition off. Check continuity of VTA2 circuit between sub-throttle position sensor and ECM. Repair as needed. Ensure circuit is not shorted to ground. If circuit is okay, adjust or replace sub-throttle position sensor.
  7. Turn ignition on. Backprobing TRAC ECU harness connector T13, measure voltage between ground and terminal No. 22. Monitor voltage while opening sub-throttle valve to wide open throttle. Voltage should be one volt or less with throttle fully closed, and 10-14 volts with throttle fully open. If voltage is within specification, replace TRAC ECU. If voltage is not within specification, go to next step.
  8. Turn ignition off. Disconnect TRAC ECU connector T13. Measure voltage between ground and terminal No. 22. Monitor voltage while opening sub-throttle valve to wide open throttle. Voltage should be one volt or less with throttle fully closed, and 10-14 volts with throttle fully open. If voltage is within specification, replace TRAC ECU. If voltage is not within specification, go to next step.
  9. Turn ignition off. Check continuity of IDL2 circuit between TRAC ECU and ECM. Repair as needed. Ensure circuit is not shorted to ground. If circuit is okay, adjust or replace sub-throttle position sensor.
  10. Inspect sub-throttle position sensor operation. See SYSTEM/COMPONENT TESTS article in ENGINE PERFORMANCE section. Adjust or replace as needed. If sub-throttle position sensor is okay, replace ECM.
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