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Home >> Toyota >> 2000 >> RAV4 Base, AWD, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P0505: Idle Air Control (IAC) System Circuit >> Diagnosis & Repair
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Diagnosis & Repair

  1. 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 Figure. Note engine RPM. Using a jumper wire, connect terminals TE1 and E1 at DLC No. 1 in engine compartment. See Fig 1. 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.
  2. Turn ignition off. Access ECM behind bottom center of instrument panel, in front of console. Disconnect ECM harness connector E4. See Figure. Turn ignition on. Measure voltage between ground and terminals No. 9 (Black/Yellow wire) and No. 10 (Black/Blue wire) at ECM harness connector E4. Both readings should be 9-14 volts. If either reading is not as specified, go to next step. If both readings are as specified, go to step  4.
  3. 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 2. Resistances should be 17-25 ohms (cold) or 22-29 ohms (hot). If resistances are not as specified, replace IAC valve. If resistances are as specified, repair open or short in wiring between IAC valve and ECM. See WIRING DIAGRAMS article.
  4. Check IAC valve operation. See IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, replace IAC valve. If problem does not exist, go to next step.
  5. Remove IAC valve from throttle body. Check IAC valve and passages for carbon build-up and blockage. If a problem exist, repair as necessary. If problem does not exist, replace ECM.
  6. 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, an open or short in A/C switch signal circuit may exist. Check A/C amplifier. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. Repair as necessary.
Fig 1: Installing Jumper Wire Between DLC No. 1 Terminals
G96F09526Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Identifying IAC Harness Connector Terminals
G95G31381Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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