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Home >> Suzuki >> 1992 >> Swift GT >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Idle Control System >> Idle Speed Control (ISC) >> SOHC
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Idle Speed Control (ISC): SOHC

  1. Before idle speed/ISC 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 tachometer. Using a service wire, connect terminal "D" (ground) and terminal "B" (diagnostic switch). Ensure CHECK ENGINE light indicates a Code 12. Connect duty meter between terminal "D" (ground) and terminal "F" (duty output). If idle speed and/or ISC duty are not within specification, adjust by turning idle speed adjusting screw. See ADJUSTMENTS article in the ENGINE PERFORMANCE Section. If idle is too high, go to step 3). If idle is too low, go to step 5). If idle is unchanged (even with headlights on), go to step 7).
  3. If idle is too high, and cannot be lowered, pinch ISC solenoid valve hose shut. If engine speed reduces, check ISC solenoid resistance. If ISC solenoid resistance is not 30-33 ohms, replace ISC solenoid. Ensure idle switch and circuit are okay. If Red/White wire from ECM (terminal No. A4) to ISC is not grounded, replace ECM with a known good unit and recheck system.
  4. If engine speed does not reduce, ensure air intake system is free from vacuum leaks. If there are no vacuum leaks, adjust duty and idle speed by turning idle speed adjusting screw. See ADJUSTMENTS article in the ENGINE PERFORMANCE Section. If engine speed is still not adjustable, check air valve for proper operation.
  5. If idle is too low and cannot be increased, ensure air is being drawn into ISC hose to air cleaner case. If engine speed increases, adjust duty and idle speed. If idle remains unchanged, check ISC solenoid resistance. If ISC solenoid resistance is not 30-33 ohms, replace ISC solenoid.
  6. Check for clogged ISC hose, open circuit in Red/White wire or poor connection at ISC solenoid. If okay, replace ECM with a known good unit and recheck system.
  7. If idle speed remains unchanged, turn ignition off. Disconnect ECM connector. If resistance between terminals No. A4 and A13 is 30-33 ohms, check connector terminal. If connection is okay, replace ECM with a known good unit and recheck. If resistance reading is not 30-33 ohms, check for poor terminal connection or an open wire in harness. If ECM terminal connection and wire harnesses are okay, replace ISC solenoid.
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