Check idle speed following procedures in ADJUSTMENTS article. If idle speed is as specified, go to next step. If idle speed is not as specified, follow procedures in DTC P0505 in TESTS W/CODES article.
With engine running, turn headlights on. If idle remains at specified idle speed, system is okay. If idle speed is not within specification, go to next step.
Turn ignition off. Disconnect IAC valve harness connector. Using an ohmmeter, measure resistance of opening coil and closing coil of IAC valve. See Fig 1 . If resistance is 18.8-22.8 ohms at 68°F (20°C), go to next step. If resistance is not as specified, replace IAC valve. Retest system.
Using fused jumper wires, connect battery voltage to terminal No. 2 of IAC valve. Connect terminal No. 1 to ground. Open throttle valve and blow air into IAC valve hose. Air should flow through valve. Switch ground lead to terminal No. 3. Air should not flow through IAC valve. Replace IAC valve if it does not operate as specified. If IAC valve does operate as specified, check Red/White wire, Red/Yellow wire, and Red/Black wire between IAC valve and PCM for an open or short. Repair as necessary. If wires are okay, replace PCM. Retest system.

Fig 1: Identifying IAC Valve Terminals

Courtesy of SUZUKI OF AMERICA CORP.

ISC DUTY SPECIFICATION

NOTE: Do not remove ISC actuator from throttle body; it is adjusted by manufacturer.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Idle Air Control (IAC) Valve: Notes