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Diagnosis & Repair (Using Toyota Hand-Held Tester)

WARNING: This page is about a different car, the 2000 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect hand-held tester to Data Link Connector (DLC) No. 3. See Figure. Start engine and warm to normal operating temperature. Turn all accessories off. Ensure A/C is off. Place transmission in Neutral. Note idle speed. Using hand-held tester, select ACTIVE TEST mode and switch TE1 on. Note engine RPM and compare RPM readings. If difference in engine speed is more than 100 RPM, go to step  8. If difference in engine speed is 100 RPM or less, go to next step.
  2. Turn ignition off. Turn ignition on. Using hand-held tester, check IAC valve duty ratio. If duty ratio is 27-47 percent, go to next step. If duty ratio is not 27-47 percent, replace ECM.
  3. Check operation of IAC valve. See IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If IAC valve does not operate properly, go to step  5. If IAC valve operates properly, go to next step.
  4. 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, go to step  8.
  5. Turn ignition off. Disconnect IAC valve harness connector. Turn ignition on. Measure voltage between ground and terminal No. 2 (Black wire) at IAC valve harness connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, repair power distribution circuit as necessary. See WIRING DIAGRAMS article.
  6. Check for open in Brown wire between ground and terminal No. 3 at IAC valve harness connector. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  7. Check for open or short in Black/Blue wire between IAC valve and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace IAC valve.
  8. 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 article in AIR CONDITIONING & HEATING. Repair as necessary.
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