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Diagnosis & Repair

  1. Disconnect IAC valve connector. Measure resistance between terminal B1 and terminals S1 and S3. Also, measure resistance between terminal B2 and terminals S2 and S4 at IAC valve harness connector. See Figure. If each reading is 31-61 ohms (cold) or 38-71 ohms (hot), go to next step. If any reading is not 31-61 ohms (cold) or 38-71 ohms (hot), replace IAC valve.
  2. Remove IAC valve. Connect a jumper wire between positive battery terminal and terminals B1 and B2 at IAC valve. Using another jumper wire, connect one end of jumper to negative battery terminal. Touch remaining end of jumper to IAC valve terminals S1, S2, S3 and S4, in that order. IAC valve should move to closed position.
  3. Ensure jumper is still connected between positive battery terminal and terminals B1 and B2. Using another jumper wire, connect one end of jumper to negative battery terminal. Touch remaining end of jumper to IAC valve terminals S4, S3, S2, and S1 in that order. IAC valve should move to open position.
  4. If IAC valve does not operate as specified, replace IAC valve. If IAC valve operates as specified, check for open or short circuit in wiring harness between main relay, IAC valve and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, no problem is indicated at this time. Diagnose by symptom. See TROUBLE SHOOTING - NO CODES article.
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