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Home >> Mazda >> 2001 >> MX-5 Miata Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1123: Throttle Position Stuck Open, High Input >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

  1. Ensure FREEZE FRAME DATA has been recorded. Check for related service bulletins. Repair as necessary and go to next step.
  2. Using scan tool, clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine. Using scan tool, access PID data for TP, MAF and RPM. Ensure MAF PID data is less than .7 lbs/Min and RPM PID data is more than 500RPM. If TP PID data 50 percent or less go to next step. If TP PID data is more than 50 percent, go to step  4.
  3. Using scan tool, access MAF PID data. Drive vehicle. If PID data does not change with driving conditions, check MAF sensor. See SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE & 626 article. Replace as necessary and go to step  8. If PID data changes with driving conditions, problem is intermittent. See TROUBLE SHOOTING - NO CODES article.
  4. Turn ignition off. Disconnect TP sensor connector. Check connector for loose or damaged terminals, poor contact or corrosion. Repair or replace as necessary and go to step  8. If no problem is found, go to next step.
  5. Check resistance between TP sensor harness connector terminal "B" (Black/Red wire) and ground. See Figure. If no resistance is present, go to next step. If resistance is found, repair poor connection or open circuit and go to step  8.
  6. Using ohmmeter connected to TP sensor terminals "A" and "C", check TP sensor resistance. If resistance changes smoothly when throttle is opened, go to next step. If resistance does not change smoothly, replace TP sensor and go to step  8.
  7. Disconnect appropriate Powertrain Control Module (PCM) connector. Check connector for loose or damaged terminals, poor contact or corrosion. Repair or replace as necessary and go to step  8. If no problem is found, go to next step.
  8. Reconnect all connectors. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine. Using scan tool, access PID data for TP, MAF and RPM. With MAF PID less than .7 lb/min. and engine speed more than 500 RPM, TP PID should be less than 50 percent. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P1123 is present, replace PCM and go to next step. On vehicles equipped with immobilizer system, reprogram ignition key identification numbers. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. If DTC P1123 is not present, go to next step.
  9. Cycle ignition from off to on. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to appropriate test.
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