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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 ECM harness connector E13. Measure voltage between ground and terminal No. 12. 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.
  3. 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. See SYSTEM/COMPONENT TESTS article in ENGINE PERFORMANCE section.
  4. Access throttle valve motor driver. DO NOT  disconnect connectors. Remove air intake duct at throttle body. Turn ignition on. Backprobing throttle valve motor driver connector T7, measure voltage between ground and terminal No. 4. 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 throttle valve motor driver. If voltage is not within specification, go to next step.
  5. Turn ignition off. Disconnect throttle valve motor driver connector T7. Measure voltage between ground and terminal No. 4. 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 throttle valve motor driver. If voltage is not within specification, go to next step.
  6. Turn ignition off. Check continuity of IDL2 circuit between throttle valve motor driver and ECM. Repair as needed. Ensure circuit is not shorted to ground. If circuit is okay, go to next step.
  7. 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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