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Home >> Suzuki >> 1995 >> Sidekick JS, 4D Utility, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - MFI >> Idle Control System >> Idle Air Control (IAC)
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Idle Air Control (IAC)

  1. Before idle speed/IAC duty is checked or adjusted, ensure all wires and vacuum hoses are connected securely, accelerator cable has some play, valve clearance and timing are set to specification, and all accessories are turned off.
  2. Warm engine to normal operating temperature. Connect a jumper wire between terminals "C" (ground) and "B" (diagnostic terminal) of test connector. Test terminal is located next to battery. See Fig 1 . Observe Malfunction Indicator Light (MIL). If Code 12 flashes, go to next step. If Code 12 does not flash, see appropriate Initial Diagnostic Procedure chart (Chart A-1, A-2 or A-3) in the TESTS W/CODES - MFI article.
    Fig 1: IAC Solenoid Wiring Schematic (Typical)
    G94I45201Courtesy of SUZUKI OF AMERICA CORP.
  3. Stop engine, and connect duty meter between terminals "A" (output) and "C" (ground). Check IAC duty and idle speed. If IAC duty and idle speed are correct, even with headlights on, system is functioning properly. If idle speed and/or IAC duty are incorrect, adjust by turning idle speed screw. See IDLE SPEED under IGNITION TIMING in the ADJUSTMENTS article. After adjustments, remove jumper wire and replace protective caps (if equipped). Recheck idle speed with A/C on. See the ADJUSTMENTS article.
  4. If idle speed is too high, check IAC solenoid valve resistance. If reading is not 11-14 ohms at 68°F (20°C), replace solenoid valve. If resistance is 11-14 ohms, observe duty meter. Duty meter values are relative to battery voltage. Off-duty indication percentage at zero voltage would be 100 percent and zero percent at highest battery voltage. Off-duty value should be more than 72 percent. If off-duty value is as specified, substitute a known-good ECM and recheck. Adjust duty to specification by turning idle adjusting screw. If not adjustable, check Fast Idle Air (FIA) valve for leakage. Repair or replace as necessary. If FIA valve is okay, check for shorted Light Green/Black wire.
  5. If idle speed is too low, check IAC solenoid valve resistance. If reading is not 11-14 ohms at 68°F (20°C), replace solenoid valve. If resistance is 11-14 ohms, observe duty meter. Duty values are relative to battery voltage. Off-duty indication percentage at zero voltage would be 100 percent and zero percent at highest battery voltage. Off-duty value should be 0-10 percent. On-duty reading would be 90-100 percent. If reading is as specified, substitute a known-good ECM and recheck.
  6. If idle is still too low, turn ignition off. Disconnect ECM connectors and check resistance between terminals B12 (Light Green/Black wire) and A12 (Blue/Black wire). If resistance is 11-14 ohms at 68°F (20°C), check for poor connector contacts at IAC solenoid and ECM. If contacts are okay, substitute ECM with a known-good unit and recheck. If connection and wire are okay, replace IAC solenoid.
  7. If reading is okay, disconnect IAC air hose from air intake case. Attempt to blow air into hose. Resistance should be felt. If resistance is felt, connect battery voltage to IAC solenoid valve terminals. If it is still difficult to blow air through valve, replace IAC solenoid valve.
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