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Home >> Mazda >> 2001 >> MX-5 Miata Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1518: Variable Tumble Control System (VTCS), Stuck Open >> 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. Turn ignition on. Using scan tool, access IMRCMTR PID and IMRC PID. If IMRCMTR PID changes with IMRC PID, go to next step. If IMRCMTR PID does not change with IMRC PID, problem is intermittent. See TROUBLE SHOOTING - NO CODES article.
  3. Turn ignition off. Disconnect VTCS vacuum switch connector. See SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE & 626 article for component location. Check connector for loose or damaged terminals, poor contact or corrosion. Repair as necessary and go to step  11. If no problem is found, go to next step.
  4. Turn ignition on. Disconnect VTCS vacuum switch. Connect a fused jumper wire between VTCS vacuum switch harness connector terminals while observing IMRCMTR PID on scan tool. If IMRCMTR PID switches to on, go to next step. If IMRCMTR PID does not switch to on, go to step  9.
  5. Turn ignition off. Measure continuity between ground and VTCS vacuum switch harness connector terminal "B" (Black wire). If continuity is present, go to next step. If continuity is not present, repair open in Black wire. See WIRING DIAGRAMS article. Go to step  11.
  6. Check VTCS vacuum switch operation. See SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE & 626 article. Replace as necessary and go to step  11. If VTCS vacuum switch is okay, go to next step.
  7. Check VTCS solenoid valve operation. See SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE & 626 article. Replace as necessary and go to step  11. If VTCS solenoid valve is okay, go to next step.
  8. Ensure appropriate vacuum lines are properly connected. Repair as necessary and go to step  11. If vacuum lines are okay, go to step  11.
  9. Turn ignition off. Disconnect appropriate PCM connector. Check connector for loose or damaged terminals, poor contact or corrosion. Repair as necessary and go to step  11. If no problem is found, go to next step.
  10. Measure voltage between ground and PCM harness connector terminal No. 4J (Orange wire). See Figure. If battery voltage is not present, go to next step. If battery voltage is present, repair short to power in Orange wire. See WIRING DIAGRAMS article. Go to step next step.
  11. Reconnect all connectors. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine. Using scan tool, ensure ECT PID is less than 140°F (60°C), RPM PID is less than 3500 RPM, IMRC PID is on and IMRCMTR PID is on. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P1518 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 P1518 is not present, go to next step.
  12. 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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