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B-6: Idle Air Control Valve System Check: Aerio

  1. Check engine idle speed and Idle Air Control (IAC) duty cycle. See IDLE SPEED under IDLE SPEED & MIXTURE in ON-VEHICLE ADJUSTMENTS article. If idle speed is within specification, go to next step. If idle speed is not as specified, go to step  4 .
  2. Start engine and allow it to idle until reaches normal operating temperature. Turn headlights, heater blower and rear defogger ON. If idle speed stays within specifications, this part of system is operating properly, go to next step. If idle speed drops below specification, go to step  6 .
  3. With engine running at idle speed, turn steering wheel right and left as far as it stops (only vehicles equipped with power steering system). If idle speed stays within specifications, this part of system is operating properly, go to next step. If idle speed do not stays within specifications, check power steering pressure switchsignal circuit, see POWER STEERING PRESSURE SWITCH under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. If check result is okay, go to step  6 .
  4. Turn ignition switch to LOCK position. Check for clogged air intake system, also check fast idle plunger length. See COLD (FAST) IDLE under IDLE SPEED & MIXTURE in ON-VEHICLE ADJUSTMENTS article. If check results are okay, go to next step. If check results are faulty, repair as necessary. After repair, retest system for normal operation.
  5. Check IAC valve operation referring to DTC P0505, P0506 & P0507: IDLE CONTROL SYSTEM MALFUNCTION/IDLE CONTROL SYSTEM - RPM LOWER THAN EXPECTED & IDLE CONTROL SYSTEM - RPM HIGHER THAN EXPECTED under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article. If test results are faulty, go to next step. If test results are okay, go to step  7 .
  6. Perform IAC valve component test. See IDLE AIR CONTROL VALVE under IDLE CONTROL SYSTEM in SYSTEM & COMPONENT TESTING article. If check results are faulty, repair or replace IAC valve. See IDLE AIR CONTROL VALVE under in REMOVAL & INSTALLATION article. If check results are okay, check for IAC valve circuits for open or short. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If IAC valve circuits are faulty, repair as necessary. If IAC valve circuits are okay, substitute ECM with known-good module and retest system for normal operation.
  7. Check A/C input signal to ECM. See A/C SIGNALS CIRCUIT CHECK under MISCELLANEOUS CONTROLS in SYSTEM & COMPONENT TESTING article. If input signal is okay, go to next step. If input signal is faulty, repair as necessary. After repair, retest system for normal operation.
  8. Check for malfunction at following systems and system components:
    • EGR valve malfunction.
    • Engine coolant temperature sensor malfunction.
    • Engine mechanical malfunction.
    • EVAP system malfunction.
    • High accessory engine load.
    • Throttle position sensor malfunction.
    • PCV system malfunction.
    If no malfunction is found, go to next step. If malfunction is found, repair system or replace component as necessary. After repair, retest system for normal operation.
  9. Check engine idle speed and Idle Air Control (IAC) duty cycle. See appropriate IDLE SPEED under IDLE SPEED & MIXTURE in ON-VEHICLE ADJUSTMENTS article. If idle speed and duty cycle are within specification, testing is complete. If idle speed is not as specified, check for clogged idle air passages. If problem is found, repair as necessary. If no problem is found, substitute ECM with known good module and retest system for normal operation.
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