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Home >> Suzuki >> 2000 >> Grand Vitara JLS, Standard >> 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. Ensure idle speed and IAC duty are within specifications. See IDLE SPEED in ON-VEHICLE ADJUSTMENTS article. If idle speed and IAC duty are not within specifications, go to next step. If idle speed and IAC duty are within specifications, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If all checks are okay, replace PCM. See REMOVAL, OVERHAUL & INSTALLATION article. Retest system.
  2. Check idle air control valve operation. See IDLE AIR CONTROL (IAC) VALVE under IDLE CONTROL SYSTEM in SYSTEM & COMPONENT TESTING article. If idle air control valve operates as specified, go to step  5 . If operation is not as specified, go to next step.
  3. Turn ignition off. Remove PCM cover, located below right side of instrument panel. Disconnect PCM connectors. Connect one lead of ohmmeter to PCM 28-pin connector "D" terminal No. 14 (Violet/Black wire). Connect other lead of ohmmeter to PCM 28-pin connector "D" terminals No. 15 (Light Green/Black wire), No. 24 (Violet/Yellow wire) and No. 25 (Gray/Blue wire). Resistance on all circuits should be 40-48 ohms. If resistance readings are as specified, go to next step. If resistance readings are not as specified, Check for open or short circuits on appropriate wire(s). See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If wiring and connectors are okay, replace IAC valve. See REMOVAL, OVERHAUL & INSTALLATION article. Retest system.
  4. Ensure ignition is off. Reconnect PCM connectors. Disconnect IAC valve harness connector. Turn ignition on. Using DVOM, measure voltage between ground and IAC valve harness connector terminals No. 2 and 5 (Blue/Black wires). If 10-14 volts exists on both wires, either IAC valve or PCM is defective. Replace as necessary. See REMOVAL, OVERHAUL & INSTALLATION article. If 10-14 volts does not exist on both wires, repair open in Blue/Black wire between IAC valve and main relay. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Repair as necessary and retest system.
  5. Ensure intake system does not draw extra air (vacuum leaks, air cleaner connections, etc.). Repair as necessary. If intake system is okay, go to next step.
  6. Check engine mechanical condition. See 2.5L V6 article in ENGINES. If engine mechanical condition is okay, go to next step.
  7. Check for excessive external load on engine (power steering pump, air conditioning compressor, generator and transmission). Repair or replace as necessary. If no excessive external load on engine is found, replace PCM. See REMOVAL, OVERHAUL & INSTALLATION article. Retest system.
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