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Home >> Mitsubishi >> 2001 >> Mirage ES, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0121: Throttle Position Sensor Circuit Malfunction, DTC P0122: Throttle Position Sensor Circuit Low Input Or DTC P0123: Throttle Position Sensor Circuit High Input >> Diagnostic Procedure
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Diagnostic Procedure

NOTE: After repairs, verify repair by driving vehicle according to appropriate monitor drive cycle and check for DTCs. See VERIFYING REPAIRS  .
  1. Turn ignition on. Using scan tool, check data list item No. 14 (THROTTLE POSITION SENSOR). With throttle in idle position, voltage should be 0.535-0.735 volt. With throttle in fully open position (wide open throttle), voltage should be 4.5-5.5 volts. If voltages are not as specified, go to next step. If voltages are as specified, problem is intermittent. See INTERMITTENT DIAGNOSTIC TROUBLE CODES  .
  2. Using scan tool, read data list item No. 26 (closed throttle position switch). Scan tool display should switch between ON (throttle at idle) and OFF (throttle open slightly). If display is as specified, go to next step. If display is not as specified, go to DTC P0510: CLOSED THROTTLE POSITION SWITCH MALFUNCTION  .
  3. Turn ignition off. Disconnect TP sensor 4-pin connector. Check resistance between TP sensor connector terminals No. 1 and 4 (component side). See Figure . Resistance should be 3.5-6.5 k/ohms. Check resistance between TP sensor connector terminals No. 2 and 4 (component side) while slowly opening throttle. Resistance should change smoothly in proportion to throttle opening. If resistance is not as specified, replace TP sensor. If resistance is as specified, go to next step.
  4. Turn ignition on. Check voltage between ground and TP sensor harness connector terminal No. 1 (Green/Blue wire). Voltage should be 4.8-5.2 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step  6 .
  5. Connect TP sensor connector. Turn ignition on. Backprobing, check voltage at Green/White wire between ECM connector B37 terminal No. 84 (M/T) or B76 terminal No. 78 (A/T) and ground. Voltage should be 0.3-1.0 volt with throttle at idle and 4.5-5.2 volts with throttle fully open. If voltage is not as specified, repair Green/White wire between ECM and TP sensor. If voltage is as specified, check ECM connector B37 (M/T) or B76 (A/T). If problem exists, repair connector. If problem does not exist, replace ECM. Go to step  7 .
  6. Check for opens, shorts or poor connections between TP sensor and ECM harness connector B37 (M/T) or B76 (A/T). See appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair connector or wiring as necessary. If problem does not exist, replace ECM. Go to next step.
  7. Verify repair by driving vehicle according to other monitor drive cycle and check for DTCs. See OTHER MONITOR  under OBD-II DRIVE CYCLES under VERIFYING REPAIRS. Confirm DTC P0121 - P0123 do not reset.
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