Idle Speed / Idle Air Control (IAC) Duty Inspection

Before idle speed / IAC duty check, make sure of the following.

Lead wires and hoses of engine and emission control systems are connected securely.
Accelerator cable has some play, that is, it is not tight.
All accessories (wipers, heater, lights, A/C, etc.) are out of service.
Air cleaner has been properly installed and is in good condition.
Ignition timing is within specification.
No abnormal air inhaling from air intake system.

After the items are all confirmed, check idle speed and IAC duty as follows.

NOTE: Before starting engine, place transmission gear shift lever in "Neutral" (shift selector lever to "P" range for A/T vehicle), and set parking brake and block drive wheels.

Connect SUZUKI scan tool to DLC with ignition switch OFF.
Special Tool

(A): SUZUKI scan tool

Fig 1: Connecting Suzuki Scan Tool To DLC
Courtesy of SUZUKI OF AMERICA CORP.
Warm up engine to normal operating temperature.

Check engine idle speed and IAC duty as follows:

Select "Data List" mode on scan tool to check idle speed and IAC duty.

Engine idle speed and IAC duty

ENGINE IDLE SPEED AND IAC DUTY

	A/T vehicle	M/T vehicle
All electric parts turned OFF and radiator cooling fan not operated.	Transmission selector lever position in "N" or "P" range.	Transmission selector lever position in neutral.
	750 +/- 50 r/min (rpm) IAC duty 5 - 15%
	Transmission selector lever position in "D" or "R" range.	-
	700 +/- 50 r/min (rpm) IAC duty 10 - 20%	-
Following items all turned ON. A/C switch Blower motor at max position Rear defogger Headlight (high or low) Radiator fan operated at high speed	Transmission selector lever position in "N" or "P" range.	Transmission selector lever position in neutral.
	850 +/- 50 r/min (rpm) IAC duty 20 - 30%
	Transmission selector lever position in "D" or "R" range.	-
	750 +/- 50 r/min (rpm) IAC duty 25 - 40%	-

If duty and/or idle speed is out of specifications, inspect idle air control system referring to IDLE AIR CONTROL (IAC) SYSTEM CHECK .

Check that specified engine idle speed is obtained with A/C ON if vehicle is equipped with A/C.
If not, check A/C control circuits and idle air control system.