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Diagnosis & Repair Procedure

  1. If engine system check has been performed, go to next step. If engine system check has not been performed, go to A4: ENGINE SYSTEM CHECK  under SYSTEM TESTS.
  2. Check idle speed and idle air control duty cycle. See IDLE SPEED & MIXTURE in ON-VEHICLE ADJUSTMENTS article. If idle speed and idle air control duty cycle are as specified, problem is probably intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If idle speed and idle air control duty cycle are not as specified, go to next step.
  3. See IDLE AIR CONTROL VALVE under IDLE CONTROL SYSTEM in SYSTEM & COMPONENT TESTING article. If IAC valve operates as specified, go to step  9. If IAC valve does not operate as specified, go to next step.
  4. Turn ignition off. Disconnect ECM 28-pin harness connector C51-1. ECM is located under instrument panel, behind glove box. See Figure. Check for poor terminal contact at ECM harness connector C51-1. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST . If terminal contact is okay, go to next step.
  5. Measure resistance between ECM harness connector C51-1 terminals No. 4 (Purple/Black wire) and No. 5 (Light Green/Black wire). See Figure. Also, measure resistance between ECM harness connector C51-1 terminals No. 16 (Purple/Yellow wire) and No. 17 (Gray/Blue wire). Resistance readings on both circuits should be 51-67 ohms. If readings are as specified, connect any disconnected harness connectors and go to step  7. If readings are not as specified, go to next step.
  6. Check for open or short in Light Green/Black wire, Purple/Yellow wire, Gray/Blue wire and Purple/Black wire between IAC valve and ECM harness connector C51-1 terminals No. 5, No. 16, No. 17 and No. 4. See WIRING DIAGRAMS article. If problem is found, repair as necessary. If no problem with wiring is found, replace IAC valve. After repair, repeat DTC CONFIRMATION TEST .
  7. Disconnect IAC valve 6-pin harness connector. IAC valve is located on throttle body. Turn ignition on. Measure voltage between ground and IAC valve harness connector terminals No. 2 (Blue/Black wire) and No. 5 (Blue/Black wire), individually. See Fig 1. If voltage reading is not 10-14 volts, go to next step. If voltage reading is 10-14 volts, substitute a known good IAC valve and repeat DTC CONFIRMATION TEST . If problem persists, substitute a known good ECM, and repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
  8. Check for open in Blue/Black wire between IAC valve and main relay. See WIRING DIAGRAMS article. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST . If no problem is found, go to next step.
  9. If idle speed as tested in step  2 was higher than specified, check for vacuum leaks from intake manifold, throttle body, PCV valve and EVAP canister purge control system. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST . If idle speed as tested in step  2 was not higher than specified, go to next step.
  10. Check components or parts that could cause low idle, check following:
    • Stuck fast idle air valve.
    • Air leak between MAF sensor and throttle body.
    • Clogged idle air passages.
    • Overheated engine.
    • High accessory engine load.
    • Engine mechanical failure.
    If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
Fig 1: Identifying Idle Air Control Valve Harness Connector Terminals
G00163693Courtesy of SUZUKI OF AMERICA CORP.
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