DTC P0505: IDLE AIR CONTROL (IAC) SYSTEM CIRCUIT

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Cornelia Cook
5 years ago
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1 Page 1 of 5 DTC P0505: IDLE AIR CONTROL (IAC) SYSTEM CIRCUIT CAUTION: If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. Circuit Description ECM operates IAC valve to perform idle-up and provide feedback for target idling speed. DTC is set when idle speed continues to vary greatly from target speed. Possible causes are: Idle Air Control (IAC) valve is stuck, or remains closed. IAC valve circuit is open or shorted. A/C signal circuit is open or shorted. Air induction system malfunction. Defective ECM. Diagnostic Aids Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected. Diagnosis & Repair Start engine and warm to normal operating temperature. Turn all accessories off. Ensure A/C is off. Shift transaxle lever into Neutral. Connect scan tool to Data Link Connector (DLC) No. 3. See Fig. 3. Note engine RPM. Using a jumper wire, connect terminals TE1 and E1 at DLC No. 1 in engine compartment. See Fig. 11. Note engine RPM and compare RPM readings. If difference in engine speed is more than 100 RPM, go to step 6. If difference in engine speed is 100 RPM or less, go to next step. Turn ignition off. Access ECM behind glove box. Disconnect ECM harness connector E6. See Fig. 1. Turn ignition on. On models with California emissions, measure voltage between ground and terminals No. 16 (Red/White wire) and No. 15 (Black/Red wire) at ECM harness connector E6. See Fig. 1. On models without California emissions, measure voltage between ground and terminals No. 23 (Red/White wire) and No. 22 (Black/Red wire) at ECM harness connector E6. See Fig. 2. On all models, both reading should be 9-14 volts. If voltages are as specified, go to step 4. If either voltage is not as specified, go to next step. Turn ignition off. Disconnect IAC valve harness connector. Measure resistance between terminal No. 2 and terminals No. 1 and 3 at IAC valve (component side). See Fig. 12. Resistance should be ohms (cold) and ohms (hot). If resistance is not as specified, replace IAC valve. If resistance is as specified, repair open or short in wiring between IAC valve and ECM. See WIRING DIAGRAMS article. Check IAC valve operation. See IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace IAC valve. If problem does not exist, go to next step.

2 Page 2 of Remove IAC valve from throttle body. Check IAC valve and passages for carbon build-up and blockage. If problem exists, repair or replace as necessary. If problem does not exist, replace ECM. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, check for an open or short in A/C switch signal circuit. Check A/C amplifier. See appropriate MANUAL A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. Repair as necessary. Fig. 11: Installing Jumper Wire Between DLC No. 1 Terminals

3 Page 3 of 5 Fig. 12: Identifying IAC Harness Connector Terminals

4 Page 4 of 5 Fig. 3: Connecting Scan Tool To Data Link Connector (DLC) No. 3 Fig. 1: Identifying Engine Control Module (ECM) Harness Connector Terminals (With California Emissions)

5 Page 5 of 5 Fig. 2: Identifying Engine Control Module (ECM) Harness Connector Terminals (Without California Emissions).

2002 ENGINE PERFORMANCE. Self-Diagnostics - RAV4. Before performing testing procedures, check for any related Technical Service Bulletins (TSBs).

2002 ENGINE PERFORMANCE. Self-Diagnostics - RAV4. Before performing testing procedures, check for any related Technical Service Bulletins (TSBs). 2002 ENGINE PERFORMANCE Self-Diagnostics - RAV4 INTRODUCTION NOTE: Before performing testing procedures, check for any related Technical Service Bulletins (TSBs). To properly diagnosis and repair this