LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Suzuki >> 1996 >> X-90 4WD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P0505 - Idle Air Control (IAC) System Malfunction
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0505 - Idle Air Control (IAC) System Malfunction

  1. Ensure idle speed and IAC duty are within specifications. See IDLE SPEED in ADJUSTMENTS article. If idle speed and IAC duty are within specifications, go to step 3). If idle speed is high and IAC duty is low, or idle speed is low and IAC duty is high, go to next step. If idle speed and IAC duty are high, or idle speed and IAC duty are low, replace PCM. Retest system.
  2. Adjust idle speed and IAC duty. If adjustments can be made with idle air adjusting screw, go to next step. If adjustments can not be made with idle air adjusting screw, go to step 4).
  3. If idle speed remains within specification as headlights are turned on, check for an intermittent problem. See the appropriate TESTS W/O CODES article. If idle speed does not stay within specification, go to step 5).
  4. Ensure engine is cold. With ignition off, remove idle air adjusting screw and check for clogged passage. Clean if necessary. If passage is okay, disconnect IAC valve harness connector. Start engine. Ensure idle speed reduces gradually as engine warms. If Idle speed reduces as specified, go to next step. If idle speed does not reduce as specified, check coolant passages or air passages for restriction. If passages are okay, replace Fast Idle Air (FIA) valve. Retest system.
  5. Turn ignition off. Disconnect IAC valve hose from air intake pipe. Turn ignition on. Blow through end of hose and ensure air does not pass through valve. Turn ignition off. Using a fused jumper wire, backprobe PCM harness connector "B", terminal No. 12, (Light Green/Black wire) to ground. See Figure. Turn ignition on. Blow through end of hose and ensure air passes through valve. If operation is not as specified, go to next step. If operation is as specified, replace PCM. Retest system.
  6. Turn ignition off. Disconnect IAC valve harness connector. Using an ohmmeter, measure resistance between terminals of IAC valve. If resistance is 11-14 ohms at 68°F (20°C), go to next step. If resistance is not as specified, replace IAC valve. Retest system.
  7. Blow into disconnected IAC valve hose. Ensure air does not pass through. Using fused jumper wires, connect battery voltage to IAC valve terminals. Air should now pass through valve. Replace IAC valve if operation is not as specified. If IAC valve is okay, check IAC valve harness for open or short. Repair as necessary.
scientia non olet · About LEMON Manuals