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Home >> Suzuki >> 2001 >> Vitara JS, 2D Utility, 1.6, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0505: Idle Air Control (IAC) System Malfunction >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. Perform DTC CONFIRMATION TEST . If DTC P0505 is set, go to next step. If DTC P0505 is not set, problem is intermittent. System is okay at this time. See TROUBLE SHOOTING - NO CODES article.
  2. Turn ignition off. Connect scan tool. Ensure all wires and hoses are connected, accelerator cable has some play in it, and ignition timing is within specification. Ensure all accessories are off. Ensure air filter is okay and no vacuum leaks are present. Ensure transmission is in Park (A/T) or Neutral (M/T) and parking brake is on. Start engine and allow it to reach normal operating temperature. Using scan tool, check idle speed and IAC duty cycle. See IDLE SPEED/IDLE AIR CONTROL (IAC) DUTY CYCLE SPECIFICATIONS  table. Go to next step.
    IDLE SPEED/IAC DUTY CYCLE SPECIFICATIONS

    Idle Speed (RPM) IAC Duty Cycle (%)
    A/C Off
    700-800 2-30
    A/C On
    1.6L Engine (800-900) (1)
    2.0L Engine (750-850) (1)
    (1) Information not available from manufacturer.
  3. If idle speed and IAC duty cycle are as specified, problem is intermittent. System is okay at this time. See TROUBLE SHOOTING - NO CODES article. If idle speed and IAC duty cycle are not as specified, go to next step.
  4. Check IAC valve operation. See IDLE AIR CONTROL (IAC) VALVE under IDLE CONTROL SYSTEM in SYSTEM & COMPONENT TESTING article. If IAC valve operation is okay, go to step  9. If IAC valve operation is not okay, go to next step.
  5. Turn ignition off. Disconnect PCM 30-pin connector C51-2. Check for poor terminal contact at PCM 30-pin connector C51-2. If poor terminal contact is found, repair as necessary and go to DTC CONFIRMATION TEST . If terminal contact is okay, measure resistance between PCM 30-pin harness connector C51-2 terminals No. 3 (Light Green/Black wire) and No. 12 (Purple/Black wire). See Figure. Also measure resistance between PCM 30-pin harness connector C51-2 terminals No. 10 (Purple/Yellow wire) and No. 11 (Gray/Blue wire). Readings on both circuits should be 70-86 ohms. If readings are as specified, go to step  7. If readings are not as specified, go to next step.
  6. Check for open or short in Light Green/Black wire, Purple/Yellow wire, Gray/Blue wire and Purple/Black wire between IAC valve and PCM 30-pin connector C51-2 terminals No. 3, No. 10, No. 11 and No. 12. See WIRING DIAGRAMS article. If wires are okay, replace IAC valve and DTC CONFIRMATION TEST .
  7. Reconnect PCM 30-pin connector C51-2. Disconnect IAC valve connector. Turn ignition on and measure voltage between ground and IAC valve harness connector terminals No. 2 (Blue/Black wire) and No. 5 (Blue/Black wire), individually. If reading is not 10-14 volts, check for open in Blue/Black wire between IAC valve and main relay. See WIRING DIAGRAMS article. If reading is 10-14 volts, go to next step.
  8. Check IAC valve operation. See SYSTEM & COMPONENT TESTING article. Replace as necessary and go to DTC CONFIRMATION TEST . If IAC valve operation is okay, replace PCM and go to DTC CONFIRMATION TEST .
  9. If idle speed in step  4 was higher than specified, check for vacuum leaks from intake manifold, throttle body, PCV valve and EVAP canister purge control system. If idle speed in step  4 was not higher than specified, go to next step.
  10. Check for vacuum leaks between throttle body and MAF sensor. Also check for EGR valve malfunction (leakage from valve seat), excessive accessory engine load, plugged idle air passage, engine mechanical problems, or overheated engine.
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