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Home >> Mitsubishi >> 2002 >> Lancer ES, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0123: Throttle Position Sensor Circuit High Input >> Diagnostic Procedure
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Diagnostic Procedure

CAUTION: To prevent damage to scan tool, always turn ignition switch to LOCK position before connecting or disconnecting scan tool.
  1. Using scan tool, check throttle position sensor. Connect scan tool to data link connector. Turn ignition on. Get scan tool to the data reading mode for data list item 14: THROTTLE POSITION SENSOR. With throttle valve in idle position, voltage should be 0.335-0.935 volt. With throttle valve in full-open position, voltage should be 4.4-5.3 volts. Turn ignition switch to LOCK position. If sensor is operating properly, malfunction is intermittent. If sensor is not operating properly, go to next step.
  2. Check throttle position sensor harness connector for damage. If connector is in good condition, go to next step. If connector is not in good condition, repair or replace as necessary. After repairs, go to step  8 .
  3. Disconnect throttle position harness connector. Using a DVOM, measure continuity between throttle position sensor terminals No. 1 and ground. Resistance should be less than 2 ohms. If continuity is not as specified, go to next step. If continuity is as specified, go to step  6 .
  4. Check ECM harness connector C-115 (M/T) or PCM harness connector C-118 (A/T) for damage. If connector is in good condition, go to next step. If connector is not in good condition, repair or replace as necessary. After repairs, go to step  8 .
  5. Check for open circuit and harness damage between throttle position sensor harness connector terminal No. 2 and ECM harness connector C-115 terminal No. 92 (M/T) or PCM harness connector C-118 terminal No. 57 (A/T). If wiring harness is in good condition, replace ECM or PCM. After replacing ECM or PCM, go to step  8 . If wiring harness is not in good condition, repair wiring harness. After repairs, go to step  8 .
  6. Disconnect throttle position sensor harness connector. Measure resistance between throttle position sensor terminals No. 2 and 3. Resistance should be 2-4 k/ohms. Measure resistance between throttle position sensor terminals No. 1 and 2. Move throttle valve from idle position to full-open position. Resistance should change smoothly in proportion to the opening angle of throttle valve. If resistance is as specified, go to next step. If resistance is not as specified, replace throttle position sensor. After replacing sensor, go to step  8 .
  7. Using scan tool, check throttle position sensor. Connect scan tool to data link connector. Turn ignition on. Set scan tool to the data reading mode for data list item 14: THROTTLE POSITION SENSOR. With throttle valve in idle position, voltage should be 0.335-0.935 volt. With throttle valve in full-open position, voltage should be 4.4-5.3 volts. Turn ignition switch to LOCK position. If sensor is operating properly, malfunction is intermittent. If sensor is not operating properly, replace ECM or PCM. After replacing ECM or PCM, go to next step.
  8. Test the OBD-II drive cycle. Carry out a test drive with the drive cycle pattern. See OTHER MONITOR  under VERIFYING REPAIRS. Check for DTCs. If DTC P0123 is output, repeat diagnosis. If DTC P0123 is not output, inspection is complete.
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