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Home >> Suzuki >> 1992 >> Sidekick JS, 4D Utility >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Idle Control System >> Idle Speed Control (ISC)
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Idle Speed Control (ISC)

  1. Before idle speed/ISC duty is checked or adjusted check the following: 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. Observe CHECK ENGINE light. If Code 12 flashes, go to next step. If Code 12 does not flash, see INITIAL DIAGNOSTIC PROCEDURE chart in TESTS W/CODES article in this section.
  3. Stop engine and connect duty meter between terminals "A" (output) and "C" (ground). Check ISC duty and idle speed. If idle speed and/or ISC duty is not within specification, adjust by turning idle speed screw. See IDLE SPEED in ADJUSTMENTS article in this section. After making adjustments, remove jumper wire and replace protective caps (if equipped). Recheck idle speed with A/C on. See ADJUSTMENTS article in this section.
  4. If idle speed is too high, check ISC solenoid valve resistance. If reading is not 11-14 ohms, replace solenoid valve. If resistance is not 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 more than 72 percent. If off-duty value is as specified, replace ECM with a known good unit and recheck. Adjust duty to specification by turning idle adjusting screw. If not adjustable, check air valve for leakage or a shorted Light Green/Black wire.
  5. If idle speed is too low, check ISC solenoid valve resistance. If reading is not 11-14 ohms, ISC solenoid valve. Off-duty meter reading should be 0-10 percent. On-duty reading would be 90-100 percent. If reading is as specified, replace ECM with a known good unit and recheck.
  6. If idle is still too low, turn ignition off. Disconnect ECM connectors and check resistance between terminals No. B12 and A12. If resistance is not 11-14 ohms, replace ECM and recheck. If no change, check for a poor connection or an open wire. If connection and wire are good, replace ISC solenoid.
  7. If reading is okay, disconnect ISC air hose from air intake case. Attempt to blow air into hose; resistance should be felt. If resistance is felt, connect battery voltage to ISC solenoid valve terminals. If it is still difficult to blow air through valve, replace ISC solenoid valve.
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