DTC P0505: Idle Control System Malfunction
NOTE:
If DTC P1508 is set, trouble shoot DTC P0505 last.
- Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral until radiator fan comes on. Allow engine to idle. Using scan tool, check engine speed with no loads (headlights, blower motor, rear defogger, radiator fan and A/C off). If engine speed is not 650-750 RPM, go to next step. If engine speed is 650-750 RPM, problem is intermittent. System is okay at this time.
- If engine speed is not 650 RPM or less, go to next step. If engine speed is 650 RPM or less, disconnect Idle Air Control (IAC) valve 2-pin connector. If engine speed does not decrease and engine does not stall, replace IAC valve. If engine speed decreases or engine stalls, adjust base idle speed. See ON-VEHICLE ADJUSTMENTS article. If engine speed will not adjust to specification, clean throttle body ports.
- Turn ignition off. Remove air intake duct from throttle body. Start engine and allow it to idle. Place a finger on lower port in throttle body. See Fig 1 . If engine speed does not decrease, go to next step. If engine speed decreases, check engine coolant level and for air in cooling system. If cooling system is okay, replace fast idle thermo valve.
- Place a finger on upper port in throttle body. If engine speed does not decrease, check for vacuum leaks and ensure throttle valve is completely closed. Repair as necessary. If idle speed decreases, adjust base idle speed to specification. See IDLE SPEED & MIXTURE in ON VEHICLE ADJUSTMENTS article. If idle speed will not adjust to specification, replace IAC valve.