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Home >> Mazda >> 1999 >> MX-5 Miata Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - Tests >> Diagnostic Trouble Codes >> DTC P0122: Throttle Position (TP) Sensor Circuit Low Input Or DTC P0123: Throttle Position (TP) Sensor Circuit High Input >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. Ensure FREEZE FRAME PID data has been recorded.
  2. Inspect all applicable harness connectors. Repair as needed and go to step  10. If no problem is found, go to next step.
  3. Using scan tool, access PID/DATA MONITOR. Record PID data for TP V. Compare reading with specification. See PIN VOLTAGE/PID VALUE CHARTS article. If data is within specification, go to next step. If data is not within specification, go to step  5 (P0122) or step  7 (P01123).
  4. Slowly depress accelerator pedal to wide open throttle. Voltage should increase evenly as throttle opening is increased. If voltage change is smooth, go to step  10. If voltage change is not smooth, replace TP sensor and go to step  10.
  5. Disconnect TP sensor harness connector. Turn ignition on. Measure voltage between ground and terminal "A" (Light Green/Red wire) on harness connector. If 5 volts is present, go to next step. If 5 volts is not present, check for open or short circuit between ECT sensor and PCM terminal 2I. Repair as needed and go to step  10.
  6. Check continuity of Green/Black wire between terminal "C" on TP harness connector and terminal No. 3E on PCM harness connector. If continuity exists, go to step. If continuity does not exist, repair as needed and go to step  10.
  7. Check continuity of Black/Red wire between terminal "B" on TP harness connector and terminal No. 3F on PCM harness connector. If continuity exists, check TP sensor, then go to step. If continuity does not exist, repair as needed and go to step  10.
  8. Inspect MAF sensor. See SYSTEM & COMPONENT TESTING - EXCEPT B2500, B3000 & B4000 article. Replace as needed and go to step  10. If MAF sensor is okay, go to next step.
  9. Erase DTC. See CLEARING CODES under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION - MIATA & MILLENIA article. If DTC is present, replace PCM. If DTC is not present, intermittent poor harness connection may have caused DTC to originally set.
  10. Erase DTC. See CLEARING CODES under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION - MIATA & MILLENIA article. If DTC is present, diagnose and repair. If DTC is not present, testing is complete.
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